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PASSAGE 1 By the mid-nineteenth century, the term "icebox" had entered the American language, but ice was still only beginning to affect the diet of ordinary citizens in the United States. The ice trade grew with the growth of cities. Ice was used in hotels, taverns, and hospitals, and by some forward-looking city dealers in fresh meat, fresh fish, and butter. After the Civil War (1861-1865), as ice was used to refrigerate freight cars, it also came into household use. Even before 1880, half the ice sold in New York, Philadelphia, and Baltimore, and one-third of that sold in Boston and Chicago, went to families for their own use. This had become possible because a new household convenience, the icebox, a precursor of the modern refrigerator, had been invented. Making an efficient icebox was not as easy as we might now suppose. In the early nineteenth century, the knowledge of the physics of heat, which was essential to a science of refrigeration, was rudimentary. The commonsense notion that the best icebox was one that prevented the ice from melting was of course mistaken, for it was the melting of the ice that performed the cooling. Nevertheless, early efforts to economize ice included wrapping the ice in blankets, which kept the ice from doing its job. Not until near the end of the nineteenth century did inventors achieve the delicate balance of insulation and circulation needed for an efficient icebox. But as early as 1803, an ingenious Maryland farmer, Thomas Moore, had been on the right track. He owned a farm about twenty miles outside the city of Washington, for which the village of Georgetown was the market center. When he used an icebox of his own design to transport his butter to market, he found that customers would pass up the rapidly melting stuff in the tubs of his competitors to pay a premium price for his butter, still fresh and hard in neat, one-pound bricks. One advantage of his icebox, Moore explained, was that farmers would no longer have to travel to market at night in order to keep their produce cool.

PASSAGE 2 The geology of the Earth's surface is dominated by the particular properties of water. Present on Earth in solid, liquid, and gaseous states, water is exceptionally reactive. It dissolves, transports, and precipitates many chemical compounds and is constantly modifying the face of the Earth. Evaporated from the oceans, water vapor forms clouds, some of which are transported by wind over the continents. Condensation from the clouds provides the essential agent of continental erosion: rain. Precipitated onto the ground, the water trickles down to form brooks, streams, and rivers, constituting what are called the hydrographic network. This immense polarized network channels the water toward a single receptacle: an ocean. Gravity dominates this entire step in the cycle because water tends to minimize its potential energy by running from high altitudes toward the reference point, that is, sea level. The rate at which a molecule of water passes though the cycle is not random but is a measure of the relative size of the various reservoirs. If we define residence time as the average time for a water molecule to pass through one of the three reservoirs — atmosphere, continent, and ocean — we see that the times are very different. A water molecule stays, on average, eleven days in the atmosphere, one hundred years on a continent and forty thousand years in the ocean. This last figure shows the importance of the ocean as the principal reservoir of the hydrosphere but also the rapidity of water transport on the continents. A vast chemical separation process takes places during the flow of water over the continents. Soluble ions such as calcium, sodium, potassium, and some magnesium are dissolved and transported. Insoluble ions such as aluminum, iron, and silicon stay where they are and form the thin, fertile skin of soil on which vegetation can grow. Sometimes soils are destroyed and transported mechanically during flooding. The erosion of the continents thus results from two closely linked and interdependent processes, chemical erosion and mechanical erosion. Their respective interactions and efficiency depend on different factors.

PASSAGE 3 The Native Americans of northern California were highly skilled at basketry, using the reeds, grasses, barks, and roots they found around them to fashion articles of all sorts and sizes — not only trays, containers, and cooking pots, but hats, boats, fish traps, baby carriers, and ceremonial objects. Of all these experts, none excelled the Pomo — a group who lived on or near the coast during the 1800's, and whose descendants continue to live in parts of the same region to this day. They made baskets three feet in diameter and others no bigger than a thimble. The Pomo people were masters of decoration. Some of their baskets were completely covered with shell pendants; others with feathers that made the baskets' surfaces as soft as the breasts of birds. Moreover, the Pomo people made use of more weaving techniques than did their neighbors. Most groups made all their basketwork by twining — the twisting of a flexible horizontal material, called a weft, around stiffer vertical strands of material, the warp. Others depended primarily on coiling — a process in which a continuous coil of stiff material is held in the desired shape with tight wrapping of flexible strands. Only the Pomo people used both processes with equal ease and frequency. In addition, they made use of four distinct variations on the basic twining process, often employing more than one of them in a single article. Although a wide variety of materials was available, the Pomo people used only a few. The warp was always made of willow, and the most commonly used weft was sedge root, a woody fiber that could easily be separated into strands no thicker than a thread. For color, the Pomo people used the bark of redbud for their twined work and dyed bullrush root for black in coiled work. Though other materials were sometimes used, these four were the staples in their finest basketry. If the basketry materials used by the Pomo people were limited, the designs were amazingly varied. Every Pomo basketmaker knew how to produce from fifteen to twenty distinct patterns that could be combined in a number of different ways.

PASSAGE 4 The term "Hudson River school" was applied to the foremost representatives of nineteenth-century North American landscape painting. Apparently unknown during the golden days of the American landscape movement, which began around 1850 and lasted until the late 1860's, the Hudson River school seems to have emerged in the 1870's as a direct result of the struggle between the old and the new generations of artists, each to assert its own style as the representative American art. The older painters, most of whom were born before 1835, practiced in a mode often self-taught and monopolized by landscape subject matter and were securely established in and fostered by the reigning American art organization, the National Academy of Design. The younger painters returning home from training in Europe worked more with figural subject matter and in a bold and impressionistic technique; their prospects for patronage in their own country were uncertain, and they sought to attract it by attaining academic recognition in New York. One of the results of the conflict between the two factions was that what in previous years had been referred to as the "American", "native", or, occasionally, "New York" school — the most representative school of American art in any genre — had by 1890 become firmly established in the minds of critics and public alike as the Hudson River school. The sobriquet was first applied around 1879. While it was not intended as flattering, it was hardly inappropriate. The Academicians at whom it was aimed had worked and socialized in New York, the Hudson's port city, and had painted the river and its shores with varying frequency. Most important, perhaps, was that they had all maintained with a certain fidelity a manner of technique and composition consistent with those of America's first popular landscape artist, Thomas Cole, who built a career painting the Catskill Mountain scenery bordering the Hudson River. A possible implication in the term applied to the group of landscapists was that many of them had, like Cole, lived on or near the banks of the Hudson. Further, the river had long served as the principal route to other sketching grounds favored by the Academicians, particularly the Adirondacks and the mountains of Vermont and New Hampshire.

PASSAGE 5 Perhaps the most obvious way artistic creation reflects how people live is by mirroring the environment — the materials and technologies available to a culture. Stone, wood, tree bark, clay, and sand are generally available materials. In addition, depending on the locality, other resources may be accessible: shells, horns, gold, copper, and silver. The different uses to which societies put these materials are of interest to anthropologists who may ask, for example, why people choose to use clay and not copper when both items are available. Although there are no conclusive answers yet, the way in which a society views its environment is sometimes apparent in its choice and use of artistic materials. The use of certain metals, for example, may be reserved for ceremonial objects of special importance. Or the belief in the supernatural powers of a stone or tree may cause a sculptor to be sensitive to that material. What is particularly meaningful to anthropologist is the realization that although the materials available to a society may to some extent limit or influence what it can do artistically, the materials by no means determine what is done. Why do the artists in Japanese society rake sand into patterns; and the artists in Roman society melt sand to form glass? Moreover, even when the same material is used in the same way by members of different societies, the form or style of the work varies enormously from culture to culture. A society may simply choose to represent objects or phenomena that are important to its population. An examination of the art of the Middle Ages tells us something about the medieval preoccupation with theological doctrine. In addition to revealing the primary concerns of a society, the content of that society's art may also reflect the culture's social stratification.

PASSAGE 6 Potash (the old name for potassium carbonate) is one of the two alkalis (the other being soda, sodium carbonate) that were used from remote antiquity in the making of glass, and from the early Middle Ages in the making of soap: the former being the product of heating a mixture of alkali and sand, the latter a product of alkali and vegetable oil. Their importance in the communities of colonial North America need hardly be stressed. Potah and soda are not interchangeable for all purposes, but for glass- or soap-making either would do. Soda was obtained largely from the ashes of certain Mediterranean sea plants, potash from those of inland vegetation. Hence potash was more familiar to the early European settlers of the North American continent. The settlement at Jamestown in Virginia was in many ways a microcosm of the economy of colonial North America, and potash was one of its first concerns. It was required for the glassworks, the first factory in the British colonies, and was produced in sufficient quantity to permit the inclusion of potash in the first cargo shipped out of Jamestown. The second ship to arrive in the settlement from England included among its passengers experts in potash making. The method of making potash was simple enough. Logs was piled up and burned in the open, and the ashes collected. The ashes were placed in a barrel with holes in the bottom, and water was poured over them. The solution draining from the barrel was boiled down in iron kettles. The resulting mass was further heated to fuse the mass into what was called potash. In North America, potash making quickly became an adjunct to the clearing of land for agriculture, for it was estimated that as much as half the cost of clearing land could be recovered by the sale of potash. Some potash was exported from Maine and New Hampshire in the seventeenth century, but the market turned out to be mainly domestic, consisting mostly of shipments from the northern to the southern colonies. For despite the beginning of the trade at Jamestown and such encouragements as a series of acts "to encourage the making of potash," beginning in 1707 in South Carolina, the softwoods in the South proved to be poor sources of the substance.

PASSAGE 7 As Philadelphia grew from a small town into a city in the first half of the eighteenth century, it became an increasingly important marketing center for a vast and growing agricultural hinterland. Market days saw the crowded city even more crowded, as farmers from within a radius of 24 or more kilometers brought their sheep, cows, pigs, vegetables, cider, and other products for direct sale to the townspeople. The High Street Market was continuously enlarged throughout the period until 1736, when it reached from Front Street to Third. By 1745 New Market was opened on Second Street between Pine and Cedar. The next year the Callowhill Market began operation. Along with market days, the institution of twice-yearly fairs persisted in Philadelphia even after similar trading days had been discontinued in other colonial cities. The fairs provided a means of bringing handmade goods from outlying places to would-be buyers in the city. Linens and stockings from Germantown, for example, were popular items. Auctions were another popular form of occasional trade. Because of the competition, retail merchants opposed these as well as the fairs. Although governmental attempts to eradicate fairs and auctions were less than successful, the ordinary course of economic development was on the merchants' side, as increasing business specialization became the order of the day. Export merchants became differentiated from their importing counterparts, and specialty shops began to appear in addition to general stores selling a variety of goods. One of the reasons Philadelphia's merchants generally prospered was because the surrounding area was undergoing tremendous economic and demographic growth. They did their business, after all, in the capital city of the province. Not only did they cater to the governor and his circle, but citizens from all over the colony came to the capital for legislative sessions of the assembly and council and the meetings of the courts of justice.

PASSAGE 8 The canopy, the upper level of the trees in the rain forest, holds a plethora of climbing mammals of moderately large size, which may include monkeys, cats, civets, and porcupines. Smaller species, including such rodents as mice and small squirrels, are not as prevalent overall in high tropical canopies as they are in most habitats globally. Small mammals, being warm blooded, suffer hardship in the exposed and turbulent environment of the uppermost trees. Because a small body has more surface area per unit of weight than a large one of similar shape, it gains or loses heat more swiftly. Thus, in the trees, where shelter from heat and cold may be scarce and conditions may fluctuate, a small mammal may have trouble maintaining its body temperature. Small size makes it easy to scramble among twigs and branches in the canopy for insects, flowers, or fruit, but small mammals are surpassed, in the competition for food, by large ones that have their own tactics for browsing among food-rich twigs. The weight of a gibbon (a small ape) hanging below a branch arches the terminal leaves down so that fruit-bearing foliage drops toward the gibbon's face. Walking or leaping species of a similar or even larger size access the outer twigs either by snapping off and retrieving the whole branch or by clutching stiff branches with the feet or tail and plucking food with their hands. Small climbing animals may reach twigs readily, but it is harder for them than for large climbing animals to cross the wide gaps from on tree crown to the next that typify the high canopy. A macaque or gibbon can hurl itself farther than a mouse can: it can achieve a running start, and it can more effectively use a branch as a springboard, even bouncing on a climb several times before jumping. The forward movement of a small animal is seriously reduced by the air friction against the relatively large surface area of its body. Finally, for the many small mammals that supplement their insect diet with fruits or seeds, an inability to span open gaps between tree crowns may be problematic, since trees that yield these foods can be sparse.

PASSAGE 9 Prehistoric mammoths have been preserved in the famous tar pits of Rancho La Brea (Brea is the Spanish word for tar) in what is now the heart of Los Angeles, California. These tar pits have been known for centuries and were formerly mined for their natural asphalt, a black or brown petroleum-like substance. Thousands of tons were extracted before 1875, when it was first noticed that the tar contained fossil remains. Major excavations were undertaken that established the significance of this remarkable site. The tar pits were found to contain the remains of scores of species of animals from the last 30,000 years of the Ice Age. Since then, over 100 tons of fossils, 1.5 million from vertebrates, 2.5 million from invertebrates, have been recovered, often in densely concentrated and tangled masses. The creatures found range from insects and birds to giant ground sloth's, but a total of 17 proboscides (animals with a proboscis or long nose) — including mastodons and Columbian mammoths — have been recovered, most of them from Pit 9, the deepest bone-bearing deposit, which was excavated in 1914. Most of the fossils date to between 40,000 and 10,000 years ago. The asphalt at La Brea seeps to the surface, especially in the summer, and forms shallow puddles that would often have been concealed by leaves and dust. Unwary animals would become trapped on these thin sheets of liquid asphalt, which are extremely sticky in warm weather. Stuck, the unfortunate beasts would die of exhaustion and hunger or fall prey to predators that often also became stuck. As the animals decayed, more scavengers would be attracted and caught in their turn. Carnivores greatly outnumber herbivores in the collection: for every large herbivore, there is one saber-tooth cat, a coyote, and four wolves. The fact that some bones are heavily weathered shows that some bodies remained above the surface for weeks or months. Bacteria in the asphalt would have consumed some of the tissues other than bones, and the asphalt itself would dissolve what was left, at the same time impregnating and beautifully preserving the saturated bones, rendering them dark brown and shiny.

PASSAGE 10 One area of paleoanthropological study involves the eating and dietary habits of hominids, erect bipedal primates — including early humans. It is clear that at some stage of history, humans began to carry their food to central places, called home bases, where it was shared and consumed with the young and other adults. The use of home bases is a fundamental component of human social behavior; the common meal served at a common hearth is a powerful symbol, a mark of social unity. Home base behavior does not occur among nonhuman primates and is rare among mammals. It is unclear when humans began to use home bases, what kind of communications and social relations were involved, and what the ecological and food-choice contexts of the shift were. Work on early tools, surveys of paleoanthropological sites, development and testing of broad ecological theories, and advances in comparative primatology are contributing to knowledge about this central chapter in human prehistory. One innovative approach to these issues involves studying damage and wear on stone tools. Researchers make tools that replicate excavated specimens as closely as possible and then try to use them as the originals might have been used, in woodcutting, hunting, or cultivation. Depending on how the tool is used, characteristic chippage patterns and microscopically distinguishable polishes develop near the edges. The first application of this method of analysis to stone tools that are 1.5 million to 2 million years old indicates that, from the start, an important function of early stone tools was to extract highly nutritious food — meat and marrow — from large animal carcasses. Fossil bones with cut marks caused by stone tools have been discovered lying in the same 2-million-year-old layers that yielded the oldest such tools and the oldest hominid specimens (including humans) with larger than ape-sized brains. This discovery increases scientists' certainty about when human ancestors began to eat more meat than present-day nonhuman primates. But several questions remain unanswered: how frequently meat eating occurred; what the social implications of meat eating were; and whether the increased use of meat coincides with the beginnings of the use of home bases.

PASSAGE 11 Plants are subject to attack and infection by a remarkable variety of symbiotic species and have evolved a diverse array of mechanisms designed to frustrate the potential colonists. These can be divided into preformed or passive defense mechanisms and inducible or active systems. Passive plant defense comprises physical and chemical barriers that prevent entry of pathogens, such as bacteria, or render tissues unpalatable or toxic to the invader. The external surfaces of plants, in addition to being covered by an epidermis and a waxy cuticle, often carry spiky hairs known as trichomes, which either prevent feeding by insects or may even puncture and kill insect larvae. Other trichomes are sticky and glandular and effectively trap and immobilize insects. If the physical barriers of the plant are breached, then preformed chemicals may inhibit or kill the intruder, and plant tissues contain a diverse array of toxic or potentially toxic substances, such as resins, tannins, glycosides, and alkaloids, many of which are highly effective deterrents to insects that feed on plants. The success of the Colorado beetle in infesting potatoes, for example, seems to be correlated with its high tolerance to alkaloids that normally repel potential pests. Other possible chemical defenses, while not directly toxic to the parasite, may inhibit some essential step in the establishment of a parasitic relationship. For example, glycoproteins in plant cell walls may inactivate enzymes that degrade cell walls. These enzymes are often produced by bacteria and fungi. Active plant defense mechanisms are comparable to the immune system of vertebrate animals, although the cellular and molecular bases are fundamentally different. Both, however, are triggered in reaction to intrusion, implying that the host has some means of recognizing the presence of a foreign organism. The most dramatic example of an inducible plant defense reaction is the hypersensitive response. In the hypersensitive response, cells undergo rapid necrosis — that is, they become diseased and die — after being penetrated by a parasite; the parasite itself subsequently ceases to grow and is therefore restricted to one or a few cells around the entry site. Several theories have been put forward to explain the basis of hypersensitive resistance.

PASSAGE 12 Among the species of seabirds that use the windswept cliffs of the Atlantic coast of Canada in the summer to mate, lay eggs, and rear their young are common murres, Atlantic puffins, black-legged kittiwakes, and northern gannets. Of all the birds on these cliffs, the black-legged kittiwake gull is the best suited for nesting on narrow ledges. Although its nesting habits are similar to those of gulls that nest on flat ground, there are a number of important differences related to the cliff-nesting habit. The advantage of nesting on cliffs is the immunity it gives from foxes, which cannot scale the sheer rocks, and from ravens and other species of gulls, which have difficulty in landing on narrow ledges to steal eggs. This immunity has been followed by a relaxation of the defenses, and kittiwakes do not react to predators nearly as fiercely as do ground-nesting gulls. A colony of Bonaparte's gulls responds to the appearance of a predatory herring gull by flying up as a group with a clamor of alarm calls, followed by concerted mobbing, but kittiwakes simply ignore herring gulls, since they pose little threat to nests on cliffs. Neither do kittiwakes attempt to conceal their nest. Most gulls keep the nest area clear of droppings, and remove empty eggshells after the chicks have hatched, so that the location of the nest is not given away. Kittiwakes defecate over the edge of the nest, which keeps it clean, but this practice, as well as their tendency to leave the nest littered with eggshells, makes its location very conspicuous. On the other hand, nesting on a narrow ledge has its own peculiar problems, and kittiwake behavior has become adapted to overcome them. The female kittiwake sits when mating, whereas other gulls stand, so the pair will not overbalance and fall off the ledge. The nest is a deep cup, made of mud or seaweed, to hold the eggs safely, compared with the shallow scrape of other gulls, and the chicks are remarkably immobile until fully grown. They do not run from their nests when approached, and if they should come near to the cliff edge, they instinctively turn back.

PASSAGE 13 Any rock that has cooled and solidified from a molten state is an igneous rock. Therefore, if the Earth began as a superheated sphere in space, all the rocks making up its crust may well have been igneous and thus the ancestors of all other rocks. Even today, approximately 95 percent of the entire crust is igneous. Periodically, molten material wells out of the Earth's interior to invade the surface layers or to flow onto the surface itself. This material cools into a wide variety of igneous rocks. In the molten state, it is called magma as it pushes into the crust and lava when it runs out onto the surface. All magma consists basically of a variety of silicate minerals (high in silicon-oxygen compounds), but the chemical composition of any given flow may differ radically from that of any other. The resulting igneous rocks will reflect these differences. Igneous rocks also vary in texture as well as chemistry. Granite, for instance, is a coarse-grained igneous rock whose individual mineral crystals have formed to a size easily seen by the naked eye. A slow rate of cooling has allowed the crystals to reach this size. Normally, slow cooling occurs when the crust is invaded by magma that remains buried well below the surface. Granite may be found on the surface of the contemporary landscape, but from its coarse texture we know that it must have formed through slow cooling at a great depth and later been laid bare by erosion. Igneous rocks with this coarse-grained texture that formed at depth are called plutonic. On the other hand, if the same magma flows onto the surface and is quickly cooled by the atmosphere, the resulting rock will be fine-grained and appear quite different from granite, although the chemical composition will be identical. This kind of rock is called rhyolite. The most finely grained igneous rock is volcanic glass or obsidian, which has no crystals. Some researchers believe this is because of rapid cooling; others believe it is because of a lack of water vapor and other gases in the lava. The black obsidian cliffs of Yellowstone National Park are the result of a lava flow of basalt running head on into a glacier. Some of the glacier melted on contact, but suddenly there also appeared a huge black mass of glassy stone.

PASSAGE 14 Television has transformed politics in the United States by changing the way in which information is disseminated, by altering political campaigns, and by changing citizen's patterns of response to politics. By giving citizens independent access to the candidates, television diminished the role of the political party in the selection of the major party candidates. By centering politics on the person of the candidate, television accelerated the citizen's focus on character rather than issues. Television has altered the forms of political communication as well. The messages on which most of us rely are briefer than they once were. The stump speech, a political speech given by traveling politicians and lasting 11/2 to 2 hours, which characterized nineteenth-century political discourse, has given way to the 30-second advertisement and the 10 second "sound bite" in broadcast news. Increasingly the audience for speeches is not that standing in front of the politician but rather the viewing audience who will hear and see a snippet of the speech on the news. In these abbreviated forms, much of what constituted the traditional political discourse of earlier ages has been lost. In 15 or 30 seconds, a speaker cannot establish the historical context that shaped the issue in question, cannot detail the probable causes of the problem, and cannot examine alternative proposals to argue that one is preferable to others. In snippets, politicians assert but do not argue. Because television is an intimate medium, speaking through it require a changed political style that was more conversational, personal, and visual than that of the old-style stump speech. Reliance on television means that increasingly our political world contains memorable pictures rather than memorable words. Schools teach us to analyze words and print. However, in a word in which politics is increasingly visual, informed citizenship requires a new set of skills. Recognizing the power of television's pictures, politicians craft televisual, staged events, called pseudo-event, designed to attract media coverage. Much of the political activity we see on television news has been crafted by politicians, their speechwriters, and their public relations advisers for televised consumption. Sound bites in news and

answers to questions in debates increasingly sound like advertisements.

PASSAGE 15 Fungi, of which there are over 100,000 species, including yeasts and other single-celled organisms as well as the common molds and mushrooms, were formerly classified as members of the plant kingdom. However, in reality they are very different from plants and today they are placed in a separate group altogether. The principal reason for this is that none of them possesses chlorophyll, and since they cannot synthesize their own carbohydrates, they obtain their supplies either from the breakdown of dead organic matter or from other living organisms. Furthermore the walls of fungal cells are not made of cellulose, as those of plants are, but of another complex sugarlike polymer called chitin, the material from which the hard outer skeletons of shrimps, spiders, and insects are made. The difference between the chemical composition of the cell walls of fungi and those of plants is of enormous importance because it enables the tips of the growing hyphae, the threadlike cells of the fungus, to secrete enzymes that break down the walls of plant cells without having any effect on those of the fungus itself. It is these cellulose-destroying enzymes that enable fungi to attack anything made from wood, wood pulp, cotton, flax, or other plant material. The destructive power of fungi is impressive. They are a major cause of structural damage to building timbers, a cause of disease in animals and humans, and one of the greatest causes of agricultural losses. Entire crops can be wiped out by fungal attacks both before and after harvesting. Some fungi can grow at +50° C, while others can grow at -5° C, so even food in cold storage may not be completely safe from them. On the other hand, fungi bring about the decomposition of dead organic matter, thus enriching the soil and returning carbon dioxide to the atmosphere. They also enter into a number of mutually beneficial relationships with plants and other organisms. In addition, fungi are the source of many of the most potent antibiotics used in clinical medicine, including penicillin.

PASSAGE 16 The first flying vertebrates were true reptiles in which one of the fingers of the front limbs became very elongated, providing support for a flap of stretched skin that served as a wing. These were the pterosaurs, literally the "winged lizards." The earliest pterosaurs arose near the end of the Triassic period of the Mesozoic Era, some 70 million years before the first known fossils of true birds occur, and they presumably dominated the skies until they were eventually displaced by birds. Like the dinosaurs, some the pterosaurs became gigantic; the largest fossil discovered is of an individual that had a wingspan of 50 feet or more, larger than many airplanes. These flying reptiles had large, tooth-filled jaws, but their bodies were small and probably without the necessary powerful muscles for sustained wing movement. They must have been expert gliders, not skillful fliers, relying on wind power for their locomotion. Birds, despite sharing common reptilian ancestors with pterosaurs, evolved quite separately and have been much more successful in their dominance of the air. They are an example of a common theme in evolution, the more or less parallel development of different types of body structure and function for the same reason — in this case, for flight. Although the fossil record, as always, is not complete enough to determine definitively the evolutionary lineage of the birds or in as much detail as one would like, it is better in this case than for many other animal groups. That is because of the unusual preservation in a limestone quarry in southern Germany of Archaeopteryx, a fossil that many have called the link between dinosaurs and birds. Indeed, had it not been for the superb preservation of these fossils, they might well have been classified as dinosaurs. They have the skull and teeth of a reptile as well as a bony tail, but in the line-grained limestone in which these fossils occur there are delicate impressions of feathers and fine details of bone structure that make it clear that Archaeopteryx was a bird. All birds living today, from the great condors of the Andes to the tiniest wrens, trace their origin back to the Mesozoic dinosaurs.

PASSAGE 17 Aviculturists, people who raise birds for commercial sale, have not yet learned how to simulate the natural incubation of parrot eggs in the wild. They continue to look for better ways to increase egg production and to improve chick survival rates. When parrots incubate their eggs in the wild, the temperature and humidity of the nest are controlled naturally. Heat is transferred from the bird's skin to the top portion of the eggshell, leaving the sides and bottom of the egg at a cooler temperature. This temperature gradient may be vital to successful hatching. Nest construction can contribute to this temperature gradient. Nests of loosely arranged sticks, rocks, or dirt are cooler in temperature at the bottom where the egg contacts the nesting material. Such nests also act as humidity regulators by allowing rain to drain into the bottom sections of the nest so that the eggs are not in direct contact with the water. As the water that collects in the bottom of the nest evaporates, the water vapor rises and is heated by the incubating bird, which adds significant humidity to the incubation environment. In artificial incubation programs, aviculturists remove eggs from the nests of parrots and incubate them under laboratory conditions. Most commercial incubators heat the eggs fairly evenly from top to bottom, thus ignoring the bird's method of natural incubation, and perhaps reducing the viability and survivability of the hatching chicks. When incubators are not used, aviculturists sometimes suspend wooden boxes outdoors to use as nests in which to place eggs. In areas where weather can become cold after eggs are laid, it is very important to maintain a deep foundation of nesting material to act as insulator against the cold bottom of the box. If eggs rest against the wooden bottom in extremely cold weather conditions, they can become chilled to a point where the embryo can no longer survive. Similarly, these boxes should be protected from direct sunlight to avoid high temperatures that are also fatal to the growing embryo. Nesting material should be added in sufficient amounts to avoid both extreme temperature situations mentioned above and assure that the eggs have a soft, secure place to rest.

PASSAGE 18 During the seventeenth and eighteenth centuries, almost nothing was written about the contributions of women during the colonial period and the early history of the newly formed United States. Lacking the right to vote and absent from the seats of power, women were not considered an important force in history. Anne Bradstreet wrote some significant poetry in the seventeenth century, Mercy Otis Warren produced the best contemporary history of the American Revolution, and Abigail Adams penned important letters showing she exercised great political influence over her husband, John, the second President of the United States. But little or no notice was taken of these contributions. During these centuries, women remained invisible in history books. Throughout the nineteenth century, this lack of visibility continued, despite the efforts of female authors writing about women. These writers, like most of their male counterparts, were amateur historians. Their writings were celebratory in nature, and they were uncritical in their selection and use of sources. During the nineteenth century, however, certain feminists showed a keen sense of history by keeping records of activities in which women were engaged. National, regional, and local women's organizations compiled accounts of their doings. Personal correspondence, newspaper clippings, and souvenirs were saved and stored. These sources from the core of the two greatest collections of women's history in the United States one at the Elizabeth and Arthur Schlesinger Library at RadclifféCollege, and the other the Sophia Smith Collection at Smith College. Such sources have provided valuable materials for later generations of historians. Despite the gathering of more information about ordinary women during the nineteenth century, most of the writing about women conformed to the "great women" theory of history, just as much of mainstream American history concentrated on "great men." To demonstrate that women were making significant contributions to American life, female authors singled out women leaders and wrote biographies, or else important women produced their autobiographies. Most of these leaders were involved in public

life as reformers, activists working for women's right to vote, or authors, and were not representative at all of the great of ordinary woman. The lives of ordinary people continued, generally, to be untold in the American histories being published.

drawing young people away from farms. Such migration was particularly rapid following the Civil War (1861-1865).

PASSAGE 19 The principal difference between urban growth in Europe and in the North American colonies was the slow evolution of cities in the former and their rapid growth in the latter. In Europe they grew over a period of centuries from town economies to their present urban structure. In North America, they started as wilderness communities and developed to mature urbanism in little more than a century. In the early colonial days in North America, small cities sprang up along the Atlantic Coastline, mostly in what are now New England and Middle Atlantic states in the United States and in the lower Saint Lawrence valley in Canada. This was natural because these areas were nearest to England and France, particularly England, from which most capital goods (assets such as equipment) and many consumer goods were imported. Merchandising establishments were, accordingly, advantageously located in port cities from which goods could be readily distributed to interior settlements. Here, too, were the favored locations for processing raw materials prior to export. Boston, Philadelphia, New York, Montreal, and other cities flourished, and, as the colonies grew, these cities increased in importance. This was less true in the colonial South, where life centered around large farms, known as plantations, rather than around towns, as was the case in the areas further north along the Atlantic coastline. The local isolation and the economic self-sufficiency of the plantations were antagonistic to the development of the towns. The plantations maintained their independence because they were located on navigable streams and each had a wharf accessible to the small shipping of that day. In fact, one of the strongest factors in the selection of plantation land was the desire to have its front on a water highway. When the United States became an independent nation in 1776, it did not have a single city as large as 50,000 inhabitants, but by 1820 it had a city of more than 10,000 people, and by 1880 it had recorded a city of over one million. It was not until after 1823, after the mechanization of the spinning had weaving industries, that cities started

PASSAGE 20 In seventeenth-century colonial North America, all day-to-day cooking was done in the fireplace. Generally large, fireplaces were planned for cooking as well as for warmth. Those in the Northeast were usually four or five feet high, and in the South, they were often high enough for a person to walk into. A heavy timber called the mantel tree was used as a lintel to support the stonework above the fireplace opening. This timber might be scorched occasionally, but it was far enough in front of the rising column of heat to be safe from catching fire. Two ledges were built across from each other on the inside of the chimney. On these rested the ends of a "lug pole" from which pots were suspended when cooking. Wood from a freshly cut tree was used for the lug pole, so it would resist heat, but it had to be replaced frequently because it dried out and charred, and was thus weakened. Sometimes the pole broke and the dinner fell into the fire. When iron became easier to obtain, it was used instead of wood for lug poles, and later fireplaces had pivoting metal rods to hang pots from. Beside the fireplace and built as part of it was the oven. It was made like a small, secondary fireplace with a flue leading into the main chimney to draw out smoke. Sometimes the door of the oven faced the room, but most ovens were built with the opening facing into the fireplace. On baking days (usually once or twice a week) a roaring fire of "oven wood," consisting of brown maple sticks, was maintained in the oven until its walls were extremely hot. The embers were later removed, bread dough was put into the oven, and the oven was sealed shut until the bread was fully baked. Not all baking was done in a big oven, however. Also used was an iron "bake kettle," which looked like a stewpot on legs and which had an iron lid. This is said to have worked well when it was placed in the fireplace, surrounded by glowing wood embers, with more embers piled on its lid.

sculpture made in the United States in the late eighteenth century.

PASSAGE 21 The sculptural legacy that the new United States inherited from its colonial predecessors was far from a rich one, and in fact, in 1776 sculpture as an art form was still in the hands of artisans and craftspeople. Stone carvers engraved their motifs of skulls and crossbones and other religious icons of death into the gray slabs that we still see standing today in old burial grounds. Some skilled craftspeople made intricately carved wooden ornamentations for furniture or architectural decorations, while others caved wooden shop signs and ships' figureheads. Although they often achieved expression and formal excellence in their generally primitive style, they remained artisans skilled in the craft of carving and constituted a group distinct from what we normally think of as "sculptors" in today's use of the word. On the rare occasion when a fine piece of sculpture was desired, Americans turned to foreign sculptors, as in the 1770's when the cities of New York and Charleston, South Carolina, commissioned the Englishman Joseph Wilton to make marble statues of William Pitt. Wilton also made a lead equestrian image of King George III that was created in New York in 1770 and torn down by zealous patriots six years later. A few marble memorials with carved busts, urns, or other decorations were produced in England and brought to the colonies to be set in the walls of churches — as in King's Chapel in Boston. But sculpture as a high art, practiced by artists who knew both the artistic theory of their Renaissance-Baroque-Rococo predecessors and the various technical procedures of modeling, casting, and carving rich three-dimensional forms, was not known among Americans in 1776. Indeed, for many years thereafter, the United States had two groups from which to choose — either the local craftspeople or the imported talent of European sculptors. The eighteenth century was not one in which powered sculptural conceptions were developed. Add to this the timidity with which unschooled artisans — originally trained as stonemasons, carpenters, or cabinetmakers — attacked the medium from which they

PASSAGE 22 Throughout the nineteenth century and into the twentieth, citizens of the United States maintained a bias against big cities. Most lived on farms and in small towns and believed cities to be centers of corruption, crime, poverty, and moral degradation. Their distrust was caused, in part, by a national ideology that proclaimed farming the greatest occupation and rural living superior to urban living. This attitude prevailed even as the number of urban dwellers increased and cities became an essential feature of the national landscape. Gradually, economic reality overcame ideology. Thousands abandoned the precarious life on the farm for more secure and better paying jobs in the city. But when these people migrated from the countryside, they carried their fears and suspicious with them. These new urbanities, already convinced that cities were overwhelmed with great problems, eagerly embraced the progressive reforms that promised to bring order out of the chaos of the city. One of many reforms came in the area of public utilities. Water and sewerage systems were usually operated by municipal governments, but the gas and electric networks were privately owned. Reformers feared that the privately owned utility companies would charge exorbitant rates for these essential services and deliver them only to people who could afford them. Some city and state governments responded by regulating the utility companies, but a number of cities began to supply these services themselves. Proponents of these reforms argued that public ownership and regulation would insure widespread access to these utilities and guarantee a fair price. While some reforms focused on government and public behavior, others looked at the cities as a whole. Civic leaders, convinced that physical environment influenced human behavior, argued that cities should develop master plans to guide their future growth and development. City planning was nothing new, but the rapid industrialization and urban growth of the late nineteenth century took place without any consideration for

order. Urban renewal in the twentieth century followed several courses. Some cities introduced plans to completely rebuild the city core. Most other cities contented themselves with zoning plans for regulating future growth. Certain parts of town were restricted to residential use, while others were set aside for industrial or commercial development.

breadbaskets of North America, sending grain not only to other colonies but also to England and southern Europe, where crippling droughts in the late 1760's created a whole new market.

PASSAGE 23 Although only 1 person in 20 in the Colonial period lived in a city, the cities had a disproportionate influence on the development of North America. They were at the cutting edge of social change. It was in the cities that the elements that can be associated with modern capitalism first appeared — the use of money and commercial paper in place of barter, open competition in place of social deference and hierarchy, with an attendant rise in social disorder, and the appearance of factories using coat or water power in place of independent craftspeople working with hand tools. "The cities predicted the future," wrote historian Gary. B. Nash, "even though they were but overgrown villages compared to the great urban centers of Europe, the Middle East and China." Except for Boston, whose population stabilized at about 16,000 in 1760, cities grew by exponential leaps through the eighteenth century. In the fifteen years prior to the outbreak of the War for independence in 1775, more than 200,000 immigrants arrived on North American shores. This meant that a population the size of Boston was arriving every year, and most of it flowed into the port cities in the Northeast. Philadelphia's population nearly doubted in those years, reaching about 30,000 in 1774, New York grew at almost the same rate, reaching about 25,000 by 1775. The quality of the hinterland dictated the pace of growth of the cities. The land surrounding Boston had always been poor farm country, and by the mid-eighteenth century it was virtually stripped of its timber. The available farmland was occupied, there was little in the region beyond the city to attract immigrants. New York and Philadelphia, by contrast, served a rich and fertile hinterland laced with navigable watercourses. Scots, Irish, and Germans landed in these cities and followed the rivers inland. The regions around the cities of New York and Philadelphia became the

PASSAGE 24 The spectacular aurora light displays that appear in Earth's atmosphere around the north and south magnetic poles were once mysterious phenomena. Now, scientists have data from satellites and ground-based observations from which we know that the aurora brilliance is an immense electrical discharge similar to that occurring in a neon sign. To understand the cause of auroras, first picture the Earth enclosed by its magnetosphere, a huge region created by the Earth's magnetic field. Outside the magnetosphere, blasting toward the earth is the solar wind, a swiftly moving plasma of ionized gases with its own magnetic filed. Charged particles in this solar wind speed earthward along the solar wind's magnetic lines of force with a spiraling motion. The Earth's magnetosphere is a barrier to the solar winds, and forces the charged particles of the solar wind to flow around the magnetosphere itself. But in the polar regions, the magnetic lines of force of the Earth and of the solar wind bunch together. Here many of the solar wind's charged particles break through the magnetosphere and enter Earth's magnetic field. They then spiral back and forth between the Earth's magnetic poles very rapidly. In the polar regions, electrons from the solar wind ionize and excite the atoms and molecules of the upper atmosphere, causing them to emit aurora radiations of visible light. The colors of an aurora depend on the atoms emitting them. The dominant greenish white light comes from low energy excitation of oxygen atoms. During huge magnetic storms oxygen atoms also undergo high energy excitation and emit crimson light. Excited nitrogen atoms contribute bands of color varying from blue to violet. Viewed from outer space, auroras can be seen as dimly glowing belts wrapped around each of

the Earth's magnetic poles. Each aurora hangs like a curtain of light stretching over the polar regions and into the higher latitudes. When the solar flares that result in magnetic storms and aurora activity are very intense, aurora displays may extend as far as the southern regions of the United States. Studies of auroras have given physicists new information about the behavior of plasmas, which has helped to explain the nature of outer space and is being applied in attempts to harness energy from the fusion of atoms.

medical schools also became less popular. It was just a decade before this that many drug companies had found their vitamin sales skyrocketing and were quick to supply practicing physicians with generous samples of vitamins and literature extolling the virtue of supplementation for a variety of health-related conditions. Expectations as to the success of vitamins in disease control were exaggerated. As is known in retrospect, vitamin and mineral therapies are much less effective when applied to health-crisis conditions than when applied to long-term problems of undernutrition that lead to chronic health problems.

PASSAGE 25 The history of clinical nutrition, or the study of the relationship between health and how the body takes in and utilizes food substances, can be divided into four distinct eras: the first began in the nineteenth century and extended into the early twentieth century when it was recognized for the first time that food contained constituents that were essential for human function and that different foods provided different amounts of these essential agents. Near the end of this era, research studies demonstrated that rapid weight loss was associated with nitrogen imbalance and could only be rectified by providing adequate dietary protein associated with certain foods. The second era was initiated in the early decades of the twentieth century and might be called "the vitamin period." Vitamins came to be recognized in foods, and deficiency syndromes were described. As vitamins became recognized as essential food constituents necessary for health, it became tempting to suggest that every disease and condition for which there had been no previous effective treatment might be responsive to vitamin therapy. At that point in time, medical schools started to become more interested in having their curricula integrate nutritional concepts into the basic sciences. Much of the focus of this education was on the recognition of vitamin deficiency symptoms. Herein lay the beginning of what ultimately turned from ignorance to denial of the value of nutritional therapies in medicine. Reckless claims were made for effects of vitamins that went far beyond what could actually be achieved from the use of them. In the third era of nutritional history in the early 1950's to mid-1960s, vitamin therapy began to fall into disrepute. Concomitant with this, nutrition education in

PASSAGE 26 In July of 1994, an astounding series of events took place. The world anxiously watched as, every few hours, a hurtling chunk of comet plunged into the atmosphere of Jupiter. All of the twenty-odd fragments, collectively called comet Shoemaker-Levy 9 after its discoverers, were once part of the same object, now dismembered and strung out along the same orbit. This cometary train, glistening like a string of pearls, had been first glimpsed only a few months before its fateful impact with Jupiter, and rather quickly scientists had predicted that the fragments were on a collision course with the giant planet. The impact caused an explosion clearly visible from Earth, a bright flaming fire that quickly expanded as each icy mass incinerated itself. When each fragment slammed at 60 kilometers per second into the dense atmosphere, its immense kinetic energy was transformed into heat, producing a superheated fireball that was ejected back through the tunnel the fragment had made a few seconds earlier. The residues from these explosions left huge black marks on the face of Jupiter, some of which have stretched out to form dark ribbons. Although this impact event was of considerable scientific import, it especially piqued public curiosity and interest. Photographs of each collision made the evening television newscast and were posted on the Internet. This was possibly the most open scientific endeavor in history. The face of the largest planet in the solar system was changed before our very eyes. And for the very first time, most of humanity came to fully appreciate the fact that we ourselves live on a similar target, a world subject to

catastrophe by random assaults from celestial bodies. That realization was a surprise to many, but it should not have been. One of the great truths revealed by the last few decades of planetary exploration is that collisions between bodies of all sizes are relatively commonplace, at least in geologic terms, and were even more frequent in the early solar system.

in corresponding size categories. Each category can be weighed to make a textural determination. Although sieves work well for silt, sand, and larger particles, they are not appropriate for clay particles. Clay is far too small to sieve accurately; therefore, in soils with a high proportion of clay, the fine particles are measured on the basis of their settling velocity when suspended in water. Since clays settle so slowly, they are easily segregated from sand and silt. The water can be drawn off and evaporated, leaving a residue of clay, which can be weighed.

PASSAGE 27 The mineral particles found in soil range in size from microscopic clay particles to large boulders. The most abundant particles — sand, silt, and clay — are the focus of examination in studies of soil texture. Texture is the term used to describe the composite sizes of particles in a soil sample, typically several representative handfuls. To measure soil texture, the sand, silt, and clay particles are sorted out by size and weight. The weights of each size are then expressed as a percentage of the sample weight. In the field, soil texture can be estimated by extracting a handful of soil and squeezing the damp soil into three basic shapes; (1) cast, a lump formed by squeezing a sample in a clenched fist; (2) thread, a pencil shape formed by rolling soil between the palms; and (3) ribbon, a flatfish shape formed by squeezing a small sample between the thumb and index finger. The behavioral characteristics of the soil when molded into each of these shapes, if they can be formed at all, provide the basis for a general textural classification. The behavior of the soil in the hand test is determined by the amount of clay in the sample. Clay particles are highly cohesive, and when dampened, behave as a plastic. Therefore the higher the clay content in a sample, the more refined and durable the shapes into which it can be molded. Another method of determining soil texture involves the use of devices called sediment sieves, screens built with a specified mesh size. When the soil is filtered through a group of sieves, each with a different mesh size, the particles become grouped

PASSAGE 28 The end of the nineteenth century and the early years of the twentieth century were marked by the development of an international Art Nouveau style, characterized by sinuous lines, floral and vegetable motifs, and soft evanescent coloration. The Art Nouveau style was an eclectic one, bringing together elements of Japanese art, motifs of ancient cultures, and natural forms. The glass objects of this style were elegant in outline, although often deliberately distorted, with pale or iridescent surfaces. A favored device of the style was to imitate the iridescent surface seen on ancient glass that had been buried. Much of the Art Nouveau glass produced during the years of its greatest popularity had been generically termed "art glass." Art glass was intended for decorative purposes and relied for its effect upon carefully chosen color combinations and innovative techniques. France produced a number of outstanding exponents of the Art Nouveau style; among the most celebrated was Emile Galle (1846-1904). In the United States, Louis Comfort Tiffany (1843-1933) was the most noted exponent of this style, producing a great variety of glass forms and surfaces, which were widely copied in their time and are highly prized today. Tiffany was a brilliant designer, successfully combining ancient Egyptian, Japanese, and Persian motifs. The Art Nouveau style was a major force in the decorative arts from 1895 until 1915, although its influence continued throughout the mid-1920's. It was eventually to be

overtaken by a new school of thought known as Functionalism that had been present since the turn of the century. At first restricted to a small avant-garde group of architects and designers, Functionalism emerged as the dominant influence upon designers after the First World War. The basic tenet of the movement — that function should determine form — was not a new concept. Soon a distinct aesthetic code evolved: form should be simple, surfaces plain, and any ornament should be based on geometric relationships. This new design concept, coupled with the sharp postwar reactions to the styles and conventions of the preceding decades, created an entirely new public taste which caused Art Nouveau types of glass to fall out of favor. The new taste demanded dramatic effects of contrast, stark outline and complex textural surfaces.

$ 1,000 to $4,000 — they were usually owned by custom thresher owners who then worked their way from farm to farm during the harvest season. "Combines" were also coming into use on the great wheat ranches in California and the Pacific Northwest. These ponderous machines — sometimes pulled by as many as 40 horses — reaped the grain, threshed it, and bagged it, all in one simultaneous operation. The adoption of labor-saving machinery had a profound effect upon the sale of agricultural operations in the northern states — allowing farmers to increase vastly their crop acreage. By the end of century, a farmer employing the new machinery could plant and harvest two and half times as much corn as a farmer had using hand methods 50 years before.

PASSAGE 29 During the second half of the nineteenth century, the production of food and feed crops in the United States rose at an extraordinarily rapid rate. Corn production increased by four and a half times, hay by five times, oats and wheat by seven times. The most crucial factor behind this phenomenal upsurge in productivity was the widespread adoption of labor-saving machinery by northern farmers. By 1850 horse-drawn reaping machines that cut grain were being introduced into the major grain-growing regions of the country. Horse-powered threshing machines to separate the seeds from the plants were already in general use. However, it was the onset of the Civil War in 1861 that provided the great stimulus for the mechanization of northern agriculture. With much of the labor force inducted into the army and with grain prices on the rise, northern farmers rushed to avail themselves of the new labor-saving equipment. In 1860 there were approximately 80,000 reapers in the country; five years later there were 350,000. After the close of the war in 1865, machinery became ever more important in northern agriculture, and improved equipment was continually introduced. By 1880 a self-binding reaper had been perfected that not only cut the grain, but also gathered the stalks and bound them with twine. Threshing machines were also being improved and enlarged, and after 1870 they were increasingly powered by steam engines rather than by horses. Since steam-powered threshing machines were costly items — running from

PASSAGE 30 Butterflies are among the most extensively studied insects — it is estimated that 90 percent of the world's species have scientific names. As a consequence, they are perhaps the best group of insects for examining patterns of terrestrial biotic diversity and distribution. Butterflies also have a favorable image with the general public. Hence, they are an excellent group for communicating information on science and conservation issues such as diversity. Perhaps the aspect of butterfly diversity that has received the most attention over the past century is the striking difference in species richness between tropical and temperate regions. For example, in 1875 one biologist pointed out the diversity of butterflies in the Amazon when he mentioned that about 700 species were found within an hour's walk, whereas the total number found on the British islands did not exceed 66, and the whole of Europe supported only 321. This early comparison of tropical and temperate butterfly richness has been well confirmed. A general theory of diversity would have to predict not only this difference between temperate and tropical zones, but also patterns within each region, and how these patterns vary among different animal and plant groups. However, for butterflies, variation of species richness within temperate or tropical regions, rather man between them, is poorly understood. Indeed, comparisons of numbers of species among the

Amazon basin, tropical Asia, and Africa are still mostly "personal communication" citations, even for vertebrates. In other words, unlike comparison between temperate and tropical areas, these patterns are still in the documentation phase. In documenting geographical variation in butterfly diversity, some arbitrary, practical decisions are made. Diversity, number of species, and species richness are used synonymously; little is known about the evenness of butterfly distribution. The New World butterflies make up the preponderance of examples because they are the most familiar species. It is hoped that by focusing on them, the errors generated by imperfect and incomplete taxonomy will be minimized.

controls have artificially depressed the most important long-term determinant of profitability — rents. Consider some examples. In a recent year in Dallas, Texas, with a 16 percent rental vacancy rate but no rent control laws, 11,000 new housing units were built. In the same year, in San Francisco, California, only 2,000 units were built. The major difference? San Francisco has only a 1.6 percent vacancy rate but stringent rent control laws. In New York City, except for government-subsidized construction, the only rental units being built are luxury units, which are exempt from controls. In Santa Monica, California, new apartments are not being constructed. New office rental space and commercial developments are, however. They are exempt from rent controls.

PASSAGE 31 Rent control is the system whereby the local government tells building owners how much they can charge their tenants in rent. In the United States, rent controls date back to at least World War II. In 1943 the federal government imposed rent controls to help solve the problem of housing shortages during wartime. The federal program ended after the war, but in some locations, including New York City, controls continued. Under New York's controls, a landlord generally cannot raise rents on apartments as long as the tenants continue to renew their leases. In places such as Santa Monica, California, rent controls are more recent. They were spurred by the inflation of the 1970's, which, combined with California's rapid population growth, pushed housing prices, as well as rents, to record levels. In 1979 Santa Monica's municipal government ordered landlords to roll back their rents to the levels charged in 1978. Future rents could only go up by two-thirds as much as any increase in the overall price level. In any housing market, rental prices perform three functions: (1) promoting the efficient maintenance of existing housing and stimulating the construction of new housing, (2) allocating existing scarce housing among competing claimants, and (3) rationing use of existing housing by potential renters. One result of rent control is a decrease in the construction of new rental units. Rent

PASSAGE 32 By 1776 the fine art of painting as it had developed in western Europe up to this time had been introduced into the American colonies through books and prints, European visitors and immigrants, and traveling colonists who brought back copies (and a few original) of old master paintings and acquaintance with European art institutions. By the outbreak of the Revolution against British rule in 1776, the status of the artists had already undergone change. In the mid-eighteenth century, painters had been willing to assume such artisan-related tasks as varnishing, gilding teaching, keeping shops, and painting wheel carriages, houses, and signs. The terminology by which artists were described at the time suggests their status: "limner" was usually applied to the anonymous portrait painter up to the 1760's; "painter" characterized anyone who could paint a flat surface. By the second half of the century, colonial artists who were trained in England or educated in the classics rejected the status of laborer and thought of themselves as artists. Some colonial urban portraitists, such as John Singleton Copley, Benjamin West, and Charles Wilson Peale, consorted with affluent patrons. Although subject to fluctuations in their economic status, all three enjoyed sufficient patronage to allow them to maintain an image of themselves as professional artists, an image indicated by their custom of signing their paintings. A few art collectors James Bowdoin III of Boston, William Byrd of Virginian, and the Aliens and Hamiltons of Philadelphia

introduced European art traditions to those colonists privileged to visit their galleries, especially aspiring artists, and established in their respective communities the idea of the value of art and the need for institutions devoted to its encouragement. Although the colonists tended to favor portraits, they also accepted landscapes, historical works, and political engravings as appropriate artistic subjects. With the coming of independence from the British Crown, a sufficient number of artists and their works were available to serve nationalistic purposes. The achievements of the colonial artists, particularly those of Copley, West, and Peale, lent credence to the boast that the new nation was capable of encouraging genius and that political liberty was congenial to the development of taste — a necessary step before art could assume an important role in the new republic.

useful when the decision involves a large number of variables with complex relationships. A realistic example for many college students is the question "What will I do after graduation?" A graduate might seek a position that offers specialized training, pursue an advanced degree, or travel abroad for a year. A decision-making worksheet begins with a succinct statement of the problem that will also help to narrow it. It is important to be clear about the distinction between long-range and immediate goals because long-range goals often involve a different decision than short-range ones. Focusing on long-range goals, a graduating student might revise the question above to "What will I do after graduation that will lead to successful career?"

PASSAGE 33 Researchers in the field of psychology have found that one of the best ways to make an important decision, such as choosing a university to attend or a business to invest in, involves the utilization of a decision worksheet. Psychologists who study optimization compare the actual decisions made by people to theoretical ideal decisions to see how similar they are. Proponents of the worksheet procedure believe that it will yield optimal, that is, the best decisions. Although there are several variations on the exact format that worksheets can take, they are all similar in their essential aspects. Worksheets require defining the problem in a clear and concise way and then listing all possible solutions to the problem. Next, the pertinent considerations that will be affected by each decision are listed, and the relative importance of each consideration or consequence is determined. Each consideration is assigned a numerical value to reflect its relative importance. A decision is mathematically calculated by adding these values together. The alternative with the highest number of points emerges as the best decision. Since most important problems are multifaceted, there are several alternatives to choose from, each with unique advantages and disadvantages. One of the benefits of a pencil and paper decision-making procedure is that it permits people to deal with more variables than their minds can generally comprehend and remember. On the average, people can keep about seven ideas in their minds at once. A worksheet can be especially

PASSAGE 34 Matching the influx of foreign immigrants into the larger cities of the United States during the late nineteenth century was a domestic migration, from town and farm to city, within the United States. The country had been overwhelmingly rural at the beginning of the century, with less than 5 percent of Americans living in large towns or cities. The proportion of urban population began to grow remarkably after 1840, increasing from 11 percent that year to 28 percent by 1880 and to 46 percent by 1900. A country with only 6 cities boasting a population of more than 8,000 in 1800 had become one with 545 such cities in 1900. Of these, 26 had a population of more than 100,000 including 3 that held more than a million people. Much of the migration producing an urban society came from smaller towns within the United States, but the combination of new immigrants and old American "settlers" on America's "urban frontier" in the late nineteenth century proved extraordinary. The growth of cities and the process of industrialization fed on each other. The agricultural revolution stimulated many in the countryside to seek a new life in the city and made it possible for fewer farmers to feed the large concentrations of people needed to provide a workforce for growing numbers of factories. Cities also provided ready and convenient markets for the products of industry, and huge contracts in transportation and

construction — as well as the expanded market in consumer goods — allowed continued growth of the urban sector of the overall economy of the Untied States. Technological developments further stimulated the process of urbanization. One example is the Bessemer converter (an industrial process for manufacturing steel), which provided steel girders for the construction of skyscrapers. The refining of crude oil into kerosene, and later the development of electric lighting as well as of the telephone, brought additional comforts to urban areas that were unavailable to rural Americans and helped attract many of them from the farms into the cities. In every era the lure of the city included a major psychological element for country people: the bustle and social interaction of urban life seemed particularly intriguing to those raised in rural isolation.

from its first appearance until its maximum size is achieved roughly at midday. It then continues its downward movement until it reaches a point where it jumps to the floor of the shelter. As the Sun continues to move to the west, the spot continues to move across the shelter floor and down the butte, or hill, toward a group of small boulders. If a person is seated on a certain one of these rocks as the spot reaches it, the Sun can be viewed through the calendar hole. This occurs at different times in the afternoon depending on the time of year.

PASSAGE 35 The observation of the skies has played a special part in the lives and cultures of peoples since the earliest of times. Evidence obtained from a site known as the Hole in the Rock, in Papago Park in Phoenix, Arizona, indicates that it might have been used as an observatory by a prehistoric people known as the Hohokam. The physical attributes of the site allow its use as a natural calendar/clock. The "hole" at Hole in the Rock is formed by two large overhanging rocks coming together at a point, creating a shelter with an opening large enough for several persons to pass through. The northeast-facing overhang has a smaller opening in its roof. It is this smaller hole that produces the attributes that may have been used as a calendar/clock. Because of its location in the shelter's roof, a beam of sunlight can pass through this second hole and cast a spot onto the shelter's wall and floor. This spot of light travels from west to east as the sun moves across the sky. It also moves from north to south and back again as the Earth travels around the Sun, the west-to-east movement could have been used to establish a daily clock, much like a sundial, while the north-to-south movement could have been used to establish a seasonal calendar. The spot first appears and starts down the surface of the wall of the shelter at different times of the morning depending on the time of the year. The spot grows in size

PASSAGE 36 The year 1850 may be considered the beginning of a new epoch in America art, with respect to the development of watercolor painting. In December of that year, a group of thirty artists gathered in the studio of John Falconer in New York City and drafted both a constitution and bylaws, establishing The Society for the Promotion of Painting in Water Color. In addition to securing an exhibition space in the Library Society building in lower Manhattan, the society founded a small school for the instruction of watercolor painting. Periodic exhibitions of the members' paintings also included works by noted English artists of the day, borrowed from embryonic private collections in the city. The society's activities also included organized sketching excursions along the Hudson River. Its major public exposure came in 1853, when the society presented works by its members in the "Industry of All Nations" section of the Crystal Palace Exposition in New York. The society did not prosper, however, and by the time of its annual meeting in 1854 membership had fallen to twenty-one. The group gave up its quarters in the Library Society building and returned to Falconer's studio, where it broke up amid dissension. No further attempt to formally organize the growing numbers of watercolor painters in New York City was made for more than a decade. During that decade, though, Henry

Warren's Painting in Water Color was published in New York City in 1856 — the book was a considerable improvement over the only other manual of instruction existing at the time, Elements of Graphic Art, by Archibald Roberson, published in 1802 and by the 1850's long out of print. In 1866 the National Academy of Design was host to an exhibition of watercolor painting in its elaborate neo-Venetian Gothic building on Twenty-Third Street in New York City. The exhibit was sponsored by an independent group called The Artists Fund Society. Within a few months of this event, forty-two prominent artists living in and near New York City founded The American Society of Painters in Water Colors.

of artistic, political, or pedagogic communication. Second, the voice gives psychological clues to a person's self-image, perception of others, and emotional health. Self-image can be indicated by a tone of voice that is confident, pretentious, shy, aggressive, outgoing, or exuberant, to name only a few personality traits. Also the sound may give a clue to the facade or mask of that person, for example, a shy person hiding behind an overconfident front. How a speaker perceives the listener's receptiveness, interest, or sympathy in any given conversation can drastically alter the tone of presentation, by encouraging or discouraging the speaker. Emotional health is evidenced in the voice by free and melodic sounds of the happy, by constricted and harsh sound of the angry, and by dull and lethargic qualities of the depressed.

PASSAGE 37 A number of factors related to the voice reveal the personality of the speaker. The first is the broad area of communication, which includes imparting information by use of language, communicating with a group or an individual, and specialized communication through performance. A person conveys thoughts and ideas through choice of words, by a tone of voice that is pleasant or unpleasant, gentle or harsh, by the rhythm that is inherent within the language itself, and by speech rhythms that are flowing and regular or uneven and hesitant, and finally, by the pitch and melody of the utterance. When speaking before a group, a person's tone may indicate unsureness or fright, confidence or calm. At interpersonal levels, the tone may reflect ideas and feelings over and above the words chosen, or may belie them. Here the conversant's tone can consciously or unconsciously reflect intuitive sympathy or antipathy, lack of concern or interest, fatigue, anxiety, enthusiasm or excitement, all of which are usually discernible by the acute listener. Public performance is a manner of communication that is highly specialized with its own techniques for obtaining effects by voice and /or gesture. The motivation derived from the text, and in the case of singing, the music, in combination with the performer's skills, personality, and ability to create empathy will determine the success

PASSAGE 38 During most of their lives, surge glaciers behave like normal glaciers, traveling perhaps only a couple of inches per day. However, at intervals of 10 to 100 years, these glaciers move forward up to 100 times faster than usual. The surge often progresses along a glacier like a great wave, proceeding from one section to another. Subglacial streams of meltwater might act as a lubricant, allowing the glacier to flow rapidly toward the sea. The increasing water pressure under the glacier might lift it off its bed, overcoming the friction between ice and rock, thus freeing the glacier, which rapidly sliders downhill. Surge glaciers also might be influenced by the climate, volcanic heat, or earthquakes. However, many of these glaciers exist in the same area as normal glaciers, often almost side by side. Some 800 years ago, Alaska's Hubbard Glacier advanced toward the sea, retreated, and advanced again 500 years later. Since 1895, this seventy-mile-long river of ice has been flowing steadily toward the Gulf of Alaska at a rate of approximately 200 feet per year. In June 1986, however, the glacier surged ahead as much as 47 feet a day. Meanwhile, a western tributary, called Valerie Glacier, advanced up to 112 feet a day.

Hubbard's surge closed off Russell Fiord with a formidable ice dam, some 2,500 feet wide and up to 800 feet high, whose caged waters threatened the town of Yakutat to the south. About 20 similar glaciers around the Gulf of Alaska are heading toward the sea. If enough surge glaciers reach the ocean and raise sea levels, west Antarctic ice shelves could rise off the seafloor and become adrift. A flood of ice would then surge into the Southern Sea. With the continued rise in sea level, more ice would plunge into the ocean, causing sea levels to rise even higher, which in turn would release more ice and set in motion a vicious cycle. The additional sea ice floating toward the tropics would increase Earth's albedo and lower global temperatures, perhaps enough to initiate a new ice age. This situation appears to have occurred at the end of the last warm interglacial (the time between glacations), called the Sangamon, when sea ice cooled the ocean dramatically, spawning the beginning of the Ice Age.

The women used their tools to process all of the fish and marine mammals brought in by the men. They cleaned the fish, and dried vast quantities of them for the winter. They sun-dried fish when practical, but in the rainy climate of the coastal area they also used smokehouses to preserve tons of fish and other seafood annually. Each product had its own peculiar characteristics that demanded a particular way of cutting or drying the meat, and each task required its own cutting blades and other utensils. After drying the fish, the women pounded some of them into fish meal, which was an easily transported food used in soups, stews, or other dishes to provide protein and thickening in the absence of fresh fish or while on long trips. The woman also made a cheese-like substance from a mixture of fish and roe by aging it in storehouses or by burying it in wooden boxes or pits lined with rocks and tree leaves.

PASSAGE 39 The Native American peoples of the north Pacific Coast created a highly complex maritime culture as they invented modes of production unique to their special environment. In addition to their sophisticated technical culture, they also attained one of the most complex social organizations of any nonagricultural people in the world. In a division of labor similar to that of the hunting peoples in the interior and among foraging peoples throughout the world, the men did most of the fishing, and the women processed the catch. Women also specialized in the gathering of the abundant shellfish that lived closer to shore. They collected oysters, crabs, sea urchins, mussels, abalone, and clams, which they could gather while remaining close to their children. The maritime life harvested by the women not only provided food, but also supplied more of the raw materials for making tools than did fish gathered by the men. Of particular importance for the native tool kit before the introduction of metal was the wide knife made from the larger mussel shells, and a variety of cutting edges that could be made from other marine shells.

PASSAGE 40 According to anthropologists, people in preindustrial societies spent 3 to 4 hours per day or about 20 hours per week doing the work necessary for life. Modern comparisons of the amount of work performed per week, however, begin with the Industrial Revolution (1760-1840) when 10- to 12-hour workdays with six workdays per week were the norm. Even with extensive time devoted to work, however, both incomes and standards of living were low. As incomes rose near the end of the Industrial Revolution, it became increasingly common to treat Saturday afternoons as a half-day holiday. The half holiday had become standard practice in Britain by the 1870's, but did not become common in the United States until the 1920's. In the United States, the first third of the twentieth century saw the workweek move from 60 hours per week to just under 50 hours by the start of the 1930's. In 1914 Henry Ford reduced daily work hours at his automobile plants from 9 to 8. In 1926 he announced that henceforth his factories would close for the entire day on Saturday. At

the time, Ford received criticism from other firms such as United States Steel and Westinghouse, but the idea was popular with workers. The Depression years of the 1930's brought with them the notion of job sharing to spread available work around; the workweek dropped to a modem low for the United States of 35 hours. In 1938 the Fair Labor Standards Act mandated a weekly maximum of 40 hours to begin in 1940, and since that time the 8-hour day, 5-day workweek has been the standard in the United States. Adjustments in various places, however, show that this standard is not immutable. In 1987, for example, German metalworkers struck for and received a 37.5-hour workweek; and in 1990 many workers in Britain won a 37-hour week. Since 1989, the Japanese government has moved from a 6- to a 5-day workweek and has set a national target of 1,800 work hours per year for the average worker. The average amount of work per year in Japan in 1989 was 2,088 hours per worker, compared to 1,957 for the United States and 1,646 for France.

Certainly, there have been periods in Earth's history when mass extinctions have occurred. The extinction of the dinosaurs was caused by some physical event, either climatic or cosmic. There have also been less dramatic extinctions, as when natural competition between species reached an extreme conclusion. Only .01 percent of the species that have lived on Earth have survived to the present, and it was largely chance that determined which species survived and which died out. However, nothing has ever equaled the magnitude and speed with which the human species is altering the physical and chemical world and demolishing the environment. In fact, there is wide agreement that it is the rate of change humans are inflicting, even more than the changes themselves, that will lead to biological devastation. Life on Earth has continually been in flux as slow physical and chemical changes have occurred on Earth, but life needs time to adapt — time for migration and genetic adaptation within existing species and time for the proliferation of new genetic material and new species that may be able to survive in new environments.

PASSAGE 41 Biological diversity has become widely recognized as a critical conservation issue only in the past two decades. The rapid destruction of the tropical rain forests, which are the ecosystems with the highest known species diversity on Earth, has awakened people to the importance and fragility of biological diversity. The high rate of species extinctions in these environments is jolting, but it is important to recognize the significance of biological diversity in all ecosystems. As the human population continues to expand, it will negatively affect one after another of Earth's ecosystems. In terrestrial ecosystems and in fringe marine ecosystems (such as wetlands), the most common problem is habitat destruction. In most situations, the result is irreversible. Now humans are beginning to destroy marine ecosystems through other types of activities, such as disposal and run off of poisonous waste; in less than two centuries, by significantly reducing the variety of species on Earth, they have unraveled cons of evolution and irrevocably redirected its course.

PASSAGE 42 Railroads reshaped the North American environment and reoriented North American behavior. "In a quarter of a century", claimed the Omaha Daily Republican in 1883, "they have made the people of the United States homogeneous, breaking through the peculiarities and provincialisms which marked separate and unmingling sections." The railroad simultaneously stripped the landscape of the natural resources, made velocity of transport and economy of scale necessary parts of industrial production, and carried consumer goods to households; it dispatched immigrants to unsettled places, drew emigrants away from farms and villages to cities, and sent men and guns to battle. It standardized time and travel, seeking to annihilate distance and space by allowing movement at any time and in any season or type of weather. In its grand and impressive terminals and stations, architects recreated historic Roman temples and public baths, French chateaus and Italian bell towers — edifices that people used as stages for many of everyday life's high emotions: meeting and parting, waiting and worrying, planning

new starts or coming home. Passenger terminals, like the luxury express trains that hurled people over spots, spotlight the romance of railroading. (The twentieth-Century Limited sped between Chicago and New York in twenty hours by 1915). Equally important to everyday life were the slow freight trans chugging through industrial zones, the morning and evening commuter locals shuttling back ions and urban terminals, and the incessant comings and goings that occurred in the classifications, or switching, yards. Moreover, in addition to its being a transportation pathway equipped with a mammoth physical plant of tracks signals, crossings, bridges, and junctions, plus telegraph and telephone lines the railroad nurtured factory complexes, coat piles, warehouses, and generating stations, forming along its right-of-way what has aptly been called "the metropolitan corridor" of the American landscape.

samples, which she then sent to her partner, who prepared extracts, isolated and purified active agents, and shipped them back to New York, where Hazen could study their biological properties. On a 1948 vacation, Hazen fortuitously collected a clump of soil from the edge of W.B. Nourse's cow pasture in Fauquier County, Virginia, that, when tested, revealed the presence of the microorganisms. In farm owner Nourse's honor, Hazen named it Streptomyces Noursei, and within a year the two scientists knew that the properties of their substance distinguished it from previously described antibiotics. After further research they eventually reduced their substance to a fine, yellow powder, which they first named "fungiciden." Then renamed "nystatin" (to honor the New York State laboratory) when they learned the previous name was already in use. Of their major discovery, Brown said lightly that it simply illustrated "how unpredictable consequences can come from rather modest beginnings."

PASSAGE 43 Elizabeth Hazen and Rachel Brown copatented one of the most widely acclaimed wonder drugs of the post-Second World War years. Hazen and Brown's work was stimulated by the wartime need to find a cure for the fungus infections that afflicted many military personnel. Scientists had been feverishly searching for an antibiotic toxic enough to kill the fungi but safe enough for human use, since, unfortunately, the new "wonder drugs" such as penicillin and streptomycin killed the very bacteria in the body that controlled the fungi. It was to discover a fungicide without that double effect that Brown, of New York State's Department of Health Laboratories at Albany, and Hazen, senior microbiologist at the Department of Health in New York, began their long-distance collaboration. Based upon Hazen's previous research at Columbia University, where she had built an impressive collection of fungus cultures, both were convinced that an antifungal organism already existed in certain soils. They divided the work. Hazen methodically screened and cultured scores of soil

PASSAGE 44 The nervous system of vertebrates is characterized by a hollow, dorsal nerve cord that ends in the head region as an enlargement, the brain. Even in its most primitive form this cord and its attached nerves are the result of evolutionary specialization, and their further evolution from lower to higher vertebrate classes is a process that is far from fully understood. Nevertheless, the basic arrangements are similar in all vertebrates, and the study of lower animals gives insight into the form and structure of the nervous system of higher animals. Moreover, for any species, the study of the embryological development of the nervous system is indispensable for an understanding of adult morphology. In any vertebrate two chief parts of the nervous system may be distinguished. These are the central nervous system (the nerve cord mentions above), consisting of the brain and spinal cord, and the peripheral nervous system, consisting of the cranial, spinal, and peripheral nerves, together with their motor and sensory endings. The term "autonomic

nervous system" refers to the parts of the central and peripheral systems that supply and regulate the activity of cardiac muscle, smooth muscle, and many glands. The nervous system is composed of many millions of nerve and glial cells, together with blood vessels and a small amount of connective tissue. The nerve cells, or "neurons", are characterized by many processes and are specialized in that they exhibit to a great degree the phenomena of irritability and conductivity. The glial cells of the central nervous system are supporting cells collectively termed "neuroglia". They are characterized by short processes that have special relationships to neurons, blood vessels, and connective tissue. The comparable cells in the peripheral nervous system are termed "neurilemmal" cells.

One impact of the new household technology was to draw sharp dividing lines between women of different classes and regions. Technological advances always affected the homes of the wealthy first, filtering downward into the urban middle class. But women who lived on farms were not yet affected by household improvements. Throughout the nineteenth century and well into the twentieth, rural homes lacked running water and electric power. Farm women had to haul large quantities of water into the house from wells or pumps for every purpose. Doing the family laundry, in large vats heated over stoves, continued to be a full day's work, just as canning and preserving continued to be seasonal necessities. Heat was provided by wood or coal stoves. In addition, rural women continued to produce most of their families' clothing. The urban poor, similarly, reaped few benefits from household improvements. Urban slums such as Chicago's nineteenth ward often had no sewers, garbage collection, or gas or electric lines; and tenements lacked both running water and central heating. At the turn of the century, variations in the nature of women's domestic work were probably more marked than at any time before.

PASSAGE 45 By the turn of the century, the middle-class home in North American had been transformed. "The flow of industry has passed and left idle the loom in the attic, the soap kettle in the shed," Ellen Richards wrote in 1908. The urban middle class was now able to buy a wide array of food products and clothing — baked goods, canned goods, suits, shirts, shoes, and dresses. Not only had household production waned, but technological improvements were rapidly changing the rest of domestic work. Middle-class homes had indoor running water and furnaces, run on oil, coal, or gas, that produced hot water. Stoves were fueled by gas, and delivery services provided ice for refrigerators. Electric power was available for lamps, sewing machines, irons, and even vacuum cleaners. No domestic task was unaffected. Commercial laundries, for instance, had been doing the wash for urban families for decades; by the early 1900's the first electric washing machines were on the market.

PASSAGE 46 Pennsylvania's colonial ironmasters forged iron and a revolution that had both industrial and political implications. The colonists in North America wanted the right to the profits gained from their manufacturing. However, England wanted all of the colonies' rich ores and raw materials to feed its own factories, and also wanted the colonies to be a market for its finished goods. England passed legislation in 1750 to prohibit colonists from making finished iron products, but by 1771, when entrepreneur Mark Bird established the Hopewell blast furnace in Pennsylvania, iron making had become the backbone of American industry. It also had become one of the major issues that fomented the revolutionary break between England and the British colonies. By the time the War of Independence broke out in 1776, Bird, angered and determined, was manufacturing cannons and shot at Hopewell to be used by the Continental Army.

After the war, Hopewell, along with hundreds of other "iron plantations," continued to form the new nation's industrial foundation well into the nineteenth century. The rural landscape became dotted with tall stone pyramids that breathed flames and smoke, charcoal-fueled iron furnaces that produced the versatile metal so crucial to the nation's growth. Generations of ironmasters, craftspeople, and workers produced goods during war and peace-ranging from cannons and shot to domestic items such as cast-iron stoves, pots, and sash weights for windows. The region around Hopewell had everything needed for iron production: a wealth of iron ore near the surface, limestone for removing impurities from the iron, hardwood forests to supply the charcoal used for fuel, rushing water to power the bellows that pumped blasts of air into the furnace fires, and workers to supply the labor. By the 1830's, Hopewell had developed a reputation for producing high quality cast-iron stoves, for which there was a steady market. As Pennsylvania added more links to its transportation system of roads, canals, and railroads, it became easier to ship parts made by Hopewell workers to sites all over the east coast. There they were assembled into stoves and sold from Rhode Island to Maryland as the "Hopewell stove". By the time the last fires burned out at Hopewell ironworks in 1883, the community had produced some 80,000 cast-iron stoves.

influence of public schools over the lives of students, many of whom in the larger industrial cities were the children of immigrants. Classes for adult immigrants were sponsored by public schools, corporations, unions, churches, settlement houses, and other agencies. Reformers early in the twentieth century suggested that education programs should suit the needs of specific populations. Immigrant women were one such population. Schools tried to educate young women so they could occupy productive places in the urban industrial economy, and one place many educators considered appropriate for women was the home. Although looking after the house and family was familiar to immigrant women, American education gave homemaking a new definition. In preindustrial economies, homemaking had meant the production as well as the consumption of goods, and it commonly included income-producing activities both inside and outside the home, in the highly industrialized early-twentieth-century United States, however, overproduction rather than scarcity was becoming a problem. Thus, the ideal American homemaker was viewed as a consumer rather than a producer. Schools trained women to be consumer homemakers cooking, shopping, decorating, and caring for children "efficiently" in their own homes, or if economic necessity demanded, as employees in the homes of others. Subsequent reforms have made these notions seem quite out-of-date.

PASSAGE 47 As the twentieth century began, the importance of formal education in the United States increased. The frontier had mostly disappeared and by 1910 most Americans lived in towns and cities. Industrialization and the bureaucratization of economic life combined with a new emphasis upon credentials and expertise to make schooling increasingly important for economic and social mobility. Increasingly, too, schools were viewed as the most important means of integrating immigrants into American society. The arrival of a great wave of southern and eastern European immigrants at the turn of the century coincided with and contributed to an enormous expansion of formal schooling. By 1920 schooling to age fourteen or beyond was compulsory in most states, and the school year was greatly lengthened. Kindergartens, vacation schools, extracurricular activities, and vocational education and counseling extended the

PASSAGE 48 According to sociologists, there are several different ways in which a person may become recognized as the leader of a social group in the United States. In the family, traditional cultural patterns confer leadership on one or both of the parents. In other cases, such as friendship groups, one or more persons may gradually emerge as leaders, although there is no formal process of selection. In larger groups, leaders are usually chosen formally through election or recruitment. Although leaders are often thought to be people with unusual personal ability, decades of research have failed to produce consistent evidence that there is any category of "natural leaders." It seems that there is no set of personal qualities that all leaders have in common; rather, virtually any person may be recognized as a leader if the person

has qualities that meet the needs of that particular group. Furthermore, although it is commonly supposed that social groups have a single leader, research suggests that there are typically two different leadership roles that are held by different individuals. Instrumental leadership is leadership that emphasizes the completion of tasks by a social group. Group members look to instrumental leaders to "get things done." Expressive leadership, on the other hand, is leadership that emphasizes the collective well-being of a social group's members. Expressive leaders are less concerned with the overall goals of the group than with providing emotional support to group members and attempting to minimize tension and conflict among them. Group members expect expressive leaders to maintain stable relationships within the group and provide support to individual members. Instrumental leaders are likely to have a rather secondary relationship to other group members. They give orders and may discipline group members who inhibit attainment of the group's goals. Expressive leaders cultivate a more personal or primary relationship to others in the group. They offer sympathy when someone experiences difficulties or is subjected to discipline, are quick to lighten a serious moment with humor, and try to resolve issues that threaten to divide the group. As the differences in these two roles suggest, expressive leaders generally receive more personal affection from group members; instrumental leaders, if they are successful in promoting group goals, may enjoy a more distant respect.

helped reduce shrinkage and cracking. Since surface finishes provided a pleasing appearance and also improved the durability in day-to-day use, the potter smoothed the exterior surface of the pot with wet hands. Often a wet clay solution, known as a slip, was applied to the smooth surface. Brightly colored slips were often used and formed painted decorations on the vessel. In later times. Glazes came into use in some areas. A glaze is a form of slip that turns to a glasslike finish during high-temperature firing. When a slip was not applied, the vessel was allowed to dry slowly until the external surface was almost like leather in texture. It was then rubbed with a round stone or similar object to give it a shiny, hard surface. Some pots were adorned with incised or stamped decorations. Most early pottery was then fired over open hearths. The vessels were covered with fast-burning wood; as it burned, the ashes would all around the pots and bake them evenly over a few hours. Far higher temperatures were attained in special ovens, known as kilns, which would not only bake the clay and remove its plasticity, but also dissolve carbons and iron compounds. Kilns were also used for glazing, when two firings were needed. Once fired, the pots were allowed to cool slowly, and small cracks were repaired before they were ready for use.

PASSAGE 49 Archaeological literature is rich in descriptions of pot making. Unlike modern industrial potters, prehistoric artisans created each of their pieces individually, using the simplest technology but demonstrating remarkable skill in making and adorning their vessels. The clay used in prehistoric pot making was invariably selected with the utmost care: often it was traded over considerable distances. The consistency of the clay was crucial: it was pounded meticulously and mixed with water to make it entirely even in texture. By careful kneading, the potter removed the air bubbles and made the clay as plastic as possible, allowing it to be molded into shape as the pot was built up, When a pot is fired, it loses its water and can crack, so the potter added a temper to the clay, a substance that

PASSAGE 50 The Arts and Crafts Movement in the United States was responsible for sweeping changes in attitudes toward the decorative arts, then considered the minor or household arts. Its focus on decorative arts helped to induce United States museums and private collectors to begin collecting furniture, glass, ceramics, metalwork, and textiles in the late nineteenth and early twentieth centuries. The fact that artisans, who were looked on as mechanics or skilled workers in the eighteenth century, are frequently considered artists today is directly attributable to the Arts and Crafts Movement of the nineteenth century. The importance now placed on attractive and harmonious home decoration can also be traced to this period, when Victorian interior arrangements were revised to admit greater light and more freely flowing spaces.

The Arts and Crafts Movement reacted against mechanized processes that threatened handcrafts and resulted in cheapened, monotonous merchandise. Founded in the late nineteenth century by British social critics John Ruskin and William Morris, the movement revered craft as a form of art. In a rapidly industrializing society, most Victorians agreed that art was an essential moral ingredient in the home environment, and in many middle- and working-class homes craft was the only form of art, Ruskin and his followers criticized not only the degradation of artisans reduced to machine operators, but also the impending loss of daily contact with handcrafted objects, fashioned with pride, integrity, and attention to beauty. In the United States as well as in Great Britain, reformers extolled the virtues of handcrafted objects: simple, straightforward design; solid materials of good quality; and sound, enduring construction techniques. These criteria were interpreted in a variety of styles, ranging from rational and geometric to romantic or naturalistic. Whether abstract, stylized, or realistically treated, the consistent theme in virtually all Arts and Crafts design is nature. The Arts and Crafts Movement was much more than a particular style; it was a philosophy of domestic life. Proponents believed that if simple design, high-quality materials, and honest construction were realized in the home and its appointments, then the occupants would enjoy moral and therapeutic effects. For both artisan and consumer, the Arts and Crafts doctrine was seen as a magical force against the undesirable effects of industrialization. PASSAGE 51 In 1972, a century after the first national park in the United States was established at Yellowstone, legislation was passed to create the National Marine Sanctuaries Program. The intent of this legislation was to provide protection to selected coastal habitats similar to that existing for land areas designated as national parks. The designation of an area's marine sanctuary indicates that it is a protected area, just as a national park is. People are permitted to visit and observe there, but living organisms and their environments may not be harmed or removed. The National Marine Sanctuaries Program is administered by the National Oceanic and Atmospheric Administration, a branch of the United States Department of Commerce. Initially, 70 sites were proposed as candidates for sanctuary status. Two and

a half decades later, only fifteen sanctuaries had been designated, with half of these established after 1978. They range in size from the very small (less than 1 square kilometer) Fagatele Bay National Marine Sanctuary in American Samoa to the Monterey Bay National Marine Sanctuary in California, extending over 15,744 square kilometers. The National Marine Sanctuaries Program is a crucial part of new management practices in which whole communities of species, and not just individual species, are offered some degree of protection from habitat degradation and overexploitation. Only in this way can a reasonable degree of marine species diversity be maintained in a setting that also maintains the natural interrelationships that exist among these species. Several other types of marine protected areas exist in the United States and other countries. The National Estuarine Research Reserve System, managed by the United States government, includes 23 designated and protected estuaries. Outside the United States, marine protected-area programs exist as marine parks, reserves, and preserves. Over 100 designated areas exist around the periphery of the Caribbean Sea. Others range from the well-known Australian Great Barrier Reef Marine Park to lesser-known parks in countries such as Thailand and Indonesia, where tourism is placing growing pressures on fragile coral reef systems. As state, national, and international agencies come to recognize the importance of conserving marine biodiversity, marine projected areas. whether as sanctuaries, parks, or estuarine reserves, will play an increasingly important role in preserving that diversity.

PASSAGE 52 In the early 1800's, over 80 percent of the United States labor force was engaged in agriculture. Sophisticated technology and machinery were virtually nonexistent. People who lived in the cities and were not directly involved in trade often participated in small cottage industries making handcrafted goods. Others cured meats, ran bakeries, or otherwise produced needed goods and commodities. Blacksmiths, silversmiths, candle makers, and other artisans worked in their homes or barns, relying on help of family members or apprentices. Perhaps no single phenomenon brought more widespread and lasting change to the United States society than the rise of industrialization. Industrial growth hinged on several economic factors. First, industry requires an abundance of natural resources,

especially coal, iron ore, water, petroleum, and timber — all readily available on the North American continent. Second, factories demand a large labor supply. Between the 1870's and the First World War (1914-1918), approximately 23 million immigrants streamed to the United States, settled in cities, and went to work in factories and mines. They also helped build the vast network of canals and railroads that crisscrossed the continent and linked important trade centers essential to industrial growth. Factories also offered a reprieve from the backbreaking work and financial unpredictability associated with farming. Many adults, poor and disillusioned with farm life, were lured to the cities by promises of steady employment, regular paychecks, increased access to goods and services, and expanded social opportunities. Others were pushed there when new technologies made their labor cheap or expendable; inventions such as steel plows and mechanized harvesters allowed one farmhand to perform work that previously had required several, thus making farming capital-intensive rather than labor-intensive. The United States economy underwent a massive transition and the nature of work was permanently altered. Whereas cottage industries relied on a few highly skilled craft workers who slowly and carefully converted raw materials into finished products from start to finish, factories relied on specialization. While factory work was less creative and more monotonous, it was also more efficient and allowed mass production of goods at less expense.

that spun glass fibers as thin as spider silk would be flexible and could be woven into fabric. By the start of the nineteenth century, glassmakers learned how to make longer, stronger fibers by pulling them from molten glass with a hot glass tube. Inventors wound the cooling end of the thread around a yarn reel, then turned the reel rapidly to pull more fiber from the molten glass. Wandering tradespeople began to spin glass fibers at fairs, making decorations and ornaments as novelties for collectors, but this material was of little practical use; the fibers were brittle, ragged, and no longer than ten feet, the circumference of the largest reels. By the mid-1870's, however, the best glass fibers were finer than silk and could be woven into fabrics or assembled into imitation ostrich feathers to decorate hats. Cloth of white spun glass resembled silver; fibers drawn from yellow-orange glass looked golden. Glass fibers were little more than a novelty until the 1930's, when their thermal and electrical insulating properties were appreciated and methods for producing continuous filaments were developed. In the modern manufacturing process, liquid glass is fed directly from a glass-melting furnace into a bushing, a receptacle pierced with hundreds of fine nozzles, from which the liquid issues in fine streams. As they solidify, the streams of glass are gathered into a single strand and wound onto a reel.

PASSAGE 53 Glass fibers have a long history. The Egyptians made coarse fibers by 1600 B.C., and fibers survive as decorations on Egyptian pottery dating back to 1375 B.C. During the Renaissance (fifteenth and sixteenth centuries A.D.), glassmakers from Venice used glass fibers to decorate the surfaces of plain glass vessels. However, glassmakers guarded their secrets so carefully that no one wrote about glass fiber production until the early seventeenth century. The eighteenth century brought the invention of "spun glass" fibers. Ré ne-Antoine de Ré aumur, a French scientist, tried to make artificial feathers from glass. He made fibers by rotating a wheel through a pool of molten glass, pulling threads of glass where the hot thick liquid stuck to the wheel. His fibers were short and fragile, but he predicted

PASSAGE 54 Composers today use a wider variety of sounds than ever before, including many that were once considered undesirable noises. Composer Edgard Varè se (1883-1965) called thus the "liberation of sound...the right to make music with any and all sounds." Electronic music, for example — made with the aid of computers, synthesizers, and electronic instruments — may include sounds that in the past would not have been considered musical. Environmental sounds, such as thunder, and electronically generated hisses and blips can be recorded, manipulated, and then incorporated into a musical composition. But composers also draw novel sounds from voices and nonelectronic instruments. Singers may be asked to scream, laugh, groan, sneeze, or to sing phonetic

sounds rather than words. Wind and string players may lap or scrape their instruments. A brass or woodwind player may hum while playing, to produce two pitches at once; a pianist may reach inside the piano to pluck a string and then run a metal blade along it. In the music of the Western world, the greatest expansion and experimentation have involved percussion instruments, which outnumber strings and winds in many recent compositions. Traditional percussion instruments are struck with new types of beaters; and instruments that used to be couriered unconventional in Western music — tom-toms, bongos, slapsticks, maracas—are widely used. In the search for novel sounds, increased use has been made in Western music of microtones. Non-western music typically divides and interval between two pitches more finely than western music does, thereby producing a greater number of distinct tones, or microtones, within the same interval. Composers such as Krzysztof Penderecki create sound that borders on electronic noise through tone clusters — closely spaced tones played together and heard as a mass, block, or band of sound. The directional aspect of sound has taken on new importance as well. Loudspeakers or groups of instruments may be placed at opposite ends of the stage, in the balcony, or at the back and sides of the auditorium. Because standard music notation makes no provision for many of these innovations, recent music scores may contain graphlike diagrams, new note shapes and symbols, and novel ways of arranging notation on the page.

that parks should be adapted to the local topography, utilize the area's trees and shrubs, and be available to the entire community. They especially emphasized the need for natural, serene settings where hurried urban dwellers could periodically escape from the city. The essence of the Olmsted park plan was to develop a continuous driveway, twenty miles long, that would tie together a whole series of parks, playgrounds, and parkways. There would be local parks and squares, too, but all of this was meant to supplement the major driveway, which was to remain the unifying factor for the entire system. In November of 1903 the city council of Seattle adopted the Olmsted Report, and it automatically became the master plan for the city's park system. Prior to this report, Seattle's park development was very limited and funding meager. All this changed after the report. Between 1907 and 1913, city voters approved special funding measures amounting to $4,000,000. With such unparalleled sums at their disposal, with the Olmsted guidelines to follow, and with the added incentive of wanting to have the city at its best for the Alaska-Yukon-Pacific Exposition of 1909, the Parks Board bought aggressively. By 1913 Seattle had 25 parks amounting to 1,400 acres, as well as 400 acres in playgrounds, pathways, boulevards, and triangles. More lands would be added in the future, but for all practical purposes it was the great land surge of 1907-1913 that established Seattle's park system.

PASSAGE 55 In 1903 the members of the governing board of the University of Washington, in Seattle, engaged a firm of landscape architects, specialists in the design of outdoor environment — Olmsted Brothers of Brookline, Massachusetts — to advise them on an appropriate layout for the university grounds. The plan impressed the university officials, and in time many of its recommendations were implemented. City officials in Seattle, the largest city in the northwestern United States, were also impressed, for they employed the same organization to study Seattle's public park needs. John Olmsted did the investigation and subsequent report on Seattle's parks. He and his brothers believed

PASSAGE 56 The term "folk song" has been current for over a hundred years, but there is still a good deal of disagreement as to what it actually means. The definition provided by the International Folk Music Council states that folk music is the music of ordinary people, which is passed on from person to person by being listened to rather than learned from the printed page. Other factors that help shape a folk song include: continuity (many performances over a number of years); variation (changes in words and melodies either through artistic interpretation or failure of memory); and selection (the acceptance of a

song by the community in which it evolves). When songs have been subjected to these processes their origin is usually impossible to trace. For instance, if a farm laborer were to make up a song and sing it to a-couple of friends who like it and memorize it, possibly when the friends come to sing it themselves one of them might forget some of the words and make up new ones to fill the gap, while the other, perhaps more artistic, might add a few decorative touches to the tune and improve a couple of lines of text. If this happened a few times there would be many different versions, the song's original composer would be forgotten, and the song would become common property. This constant reshaping and re-creation is the essence of folk music. Consequently, modem popular songs and other published music, even though widely sung by people who are not professional musicians, are not considered folk music. The music and words have been set by a printed or recorded source, limiting scope for further artistic creation. These songs' origins cannot be disguised and therefore they belong primarily to the composer and not to a community. The ideal situation for the creation of folk music is an isolated rural community. In such a setting folk songs and dances have a special purpose at every stage in a person's life, from childhood to death. Epic tales of heroic deeds, seasonal songs relating to calendar events, and occupational songs are also likely to be sung.

decoration, for example, in the interplay of black and other glazes with the red surface of the fired pot. Athenian black-figure and red-figure decoration, which emphasized human figures rather than animal images, was adopted between 630 and 530 B.C.; its distinctive color and luster were the result of the skillful adjustments of the kiln's temperature during an extended three-stage period if firing the clayware. Whether it was the potters or the vase-painters who initiated changes in firing is unclear, the functions of making and decorating were usually divided between them, but neither group can have been so specialized that they did not share in the concerns of the other. The broad utility of terra-cotta was such that workers in clay could generally afford to confine themselves to either decorated ware and housewares like cooking pots and storage jars or building materials like roof tiles and drainpipes. Some sixth- and fifth-century B.C. Athenian pottery establishments are known to have concentrated on a limited range of fine ware, but a rural pottery establishment on the island of Thasos produced many types of pottery and roof tiles too, presumably to meet local demand. Molds were used to create particular effects for some products, such as relief-decorated vessels and figurines; for other products such as roof tiles, which were in some quantity, they were used to facilitate mass production. There were also a number of poor-quality figurines and painted pots produced in quantity by easy, inexpensive means — as numerous featureless statuettes and unattractive cases testify.

PASSAGE 57 Often enough the craft worker's place of employment in ancient Greece was set in rural isolation. Potter, for instance, found it convenient to locate their workshops near their source of clay, regardless of its relation to the center of settlement. At Corinth and Athens, however, two of the best-known potters' quarters were situated on the cities' outskirts, and potters and makers of terra-cotta figurines were also established well within the city of Athens itself. The techniques of pottery manufacture had evolved well before the Greek period, but marked stylistic developments occurred in shape and in

PASSAGE 58 Hunting is at best a precarious way of procuring food, even when the diet is supplemented with seeds and fruits. Not long after the last Ice Age, around 7,000 B.C. (during the Neolithic period), some hunters and gatherers began to rely chiefly on agriculture for their sustenance. Others continued the old pastoral and nomadic ways. Indeed, agriculture itself evolved over the course of time, and Neolithic peoples had long known how to grow crops. The real transformation of human life occurred when huge numbers of people began to rely primarily and permanently on the grain they grew and

the animals they domesticated. Agriculture made possible a more stable and secure life. With it Neolithic peoples flourished, fashioning an energetic, creative era. They were responsible for many fundamental inventions and innovations that the modern world takes for granted. First, obviously, is systematic agriculture — that is, the reliance of Neolithic peoples on agriculture as their primary, not merely subsidiary, source of food. Thus they developed the primary economic activity of the entire ancient world and the basis of all modern life. With the settled routine of Neolithic farmers came the evolution of towns and eventually cities. Neolithic farmers usually raised more food than they could consume, and their surpluses permitted larger, healthier populations. Population growth in turn created an even greater reliance on settled farming, as only systematic agriculture could sustain the increased numbers of people. Since surpluses of food could also be bartered for other commodities, the Neolithic era witnessed the beginnings of large-scale exchange of goods. In time the increasing complexity of Neolithic societies led to the development of writing, prompted by the need to keep records and later by the urge to chronicle experiences, learning, and beliefs. The transition to settled life also had a profound impact on the family. The shared needs and pressures that encourage extended-family ties are less prominent in settled than in nomadic societies. Bonds to the extended family weakened. In towns and cities, the nuclear family was more dependent on its immediate neighbors than on kinfolk.

were the bones preserved in these skeletons, but also were imprints of the feathers. If the indications of feathers had not been preserved in association with Archaeopteryx, it is likely that these fossils would have been classified among the dinosaurs, for they show numerous theropod characteristics. Archaeopteryx were animals about the size of a crow, with an archeosaurian type of skull, a long neck, a compact body balanced on a pair of strong hind limbs, and a long tail. The forelimbs were enlarged and obviously functioned as wings. Modern birds, who are the descendants of these early birds, are highly organized animals, with a constant body temperature and a very high rate of metabolism. In addition, they are remarkable for having evolved extraordinarily complex behavior patterns such as those of nesting and song, and the habit among many species of making long migrations from one continent to another and back each year. Most birds also have very strong legs, which allow them to run or walk on the ground as well as to fly in the air. Indeed, some of the waterbirds, such as ducks and geese, have the distinction of being able to move around proficiently in the water, on land, and in the air, a range in natural locomotor ability that has never been attained by any other vertebrate.

PASSAGE 59 The first birds appeared during late Jurassic times. These birds are known from four very good skeletons, two incomplete skeletons, and an isolated feather, all from the Solnhofen limestone of Bavaria, Germany. This fine-grained rock, which is extensively quarried for lithographic stone, was evidently deposited in a shallow coral lagoon of a tropical sea, and flying vertebrates occasionally fell into the water and were buried by the fine limy mud, to be preserved with remarkable detail. In this way, the late Jurassic bird skeletons, which have been named Archaeopteryx, were fossilized. And not only

PASSAGE 60 By far the most important United States export product in the eighteenth and nineteenth centuries was cotton, favored by the European textile industry over flax or wool because it was easy to process and soft to tile touch. Mechanization of spinning and weaving allowed significant centralization and expansion in the textile industry during this period, and at the same time the demand for cotton increased dramatically.

American producers were able to meet this demand largely because of tile invention of the cotton gin by Eli Whitney in 1793. Cotton could be grown throughout the South, but separating the fiber — or lint — from the seed was a laborious process. Sea island cotton was relatively easy to process by hand, because its fibers were long and seeds were concentrated at the base of the flower, but it demanded a long growing season, available only along the nation's eastern seacoast. Short-staple cotton required a much shorter growing season, but the shortness of the fibers and their mixture with seeds meant that a worker could hand-process only about one pound per day. Whitney's gin was a hand-powered machine with revolving drums and metal teeth to pull cotton fibers away from seeds. Using the gin, a worker could produce up to 50 pounds of lint a day. The later development of larger gins, powered by horses, water, or steam, multiplied productivity further. The interaction of improved processing and high demand led to the rapid spread of the cultivation of cotton and to a surge in production. It became the main American export, dwarfing all others. In 1802, cotton composed 14 percent of total American exports by value. Cotton had a 36 percent share by 1810 and over a 50 percent share in 1830. In 1860, 61 percent of the value of American exports was represented by cotton. In contrast, wheat and wheat flour composed only 6 percent of the value of American exports in that year. Clearly, cotton was king in the trade of the young republic. The growing market for cotton and other American agricultural products led to an unprecedented expansion of agricultural settlement, mostly in the eastern half of the United States — west of the Appalachian Mountains and east of the Mississippi River.

apprentice as an assistant, the rural artisan provided the neighborhood with common goods from furniture to shoes to farm equipment in exchange for cash or for "goods in kind" from the customer's field, pasture, or dairy. Sometimes artisans transformed material provided by the customer; wove cloth of yarn spun at the farm from the wool of the family sheep; made chairs or tables from wood cut in the customer's own woodlot; produced shoes or leather breeches from cow, deer, or sheepskin tanned on the farm. Like their farming neighbors, rural artisans were part of an economy scene, by one historian, as "an orchestra conducted by nature." Some tasks could not be done in the winter, other had to be put off during harvest time, and still others waited on raw materials that were only produced seasonally. As the days grew shorter, shop hours kept pace, since few artisans could afford enough artificial light to continue work when the Sun went down. To the best of their ability, colonial artisans tried to keep their shops as efficient as possible and to regularize their schedules and methods of production for the best return on their investment in time, tools, and materials. While it is pleasant to imagine a woodworker, for example, carefully matching lumber, joining a chest together without resort to nails or glue, and applying all thought and energy to carving beautiful designs on the finished piece, the time required was not justified unless the customer was willing to pay extra for the quality — and few in rural areas were. Artisans, therefore, often found it necessary to employ as many shortcuts and economics as possible while still producing satisfactory products.

PASSAGE 61 From their inception, most rural neighborhoods in colonial North America included at least one carpenter, joiner, sawyer, and cooper in woodworking; a weaver and a tailor for clothing production; a tanner, currier, and cordwainer (shoemaker) for fabricating leather objects; and a blacksmith for metalwork. Where stone was the local building material, a mason was sure to appear on the list of people who paid taxes. With only an

PASSAGE 62 Molting is one of the most involved processes of a bird's annual life cycle. Notwithstanding preening and constant care, the marvelously intricate structure of a bird's feather inevitably wears out. All adult birds molt their feathers at least once a year, and upon close observation, one can recognize the frayed, ragged appearance of feathers that are nearing the end of their useful life. Two distinct processes are involved in

molting. The first step is when the old, worn feather is dropped, or shed. The second is when a new feather grows in its place. When each feather has been shed and replaced, then the molt can be said to be complete. This, however, is an abstraction that often does not happen: incomplete, overlapping, and arrested molts are quite common. Molt requires that a bird find and process enough protein to rebuild approximately one-third of its body weight. It is not surprising that a bird in heavy molt often seems listless and unwell. But far from being random, molt is controlled by strong evolutionary forces that have established an optimal time and duration. Generally, molt occurs at the time of least stress on the bird. Many songbirds, for instance, molt in late summer, when the hard work of breeding is done but the weather is still warm and food still plentiful. This is why the woods in late summer often seem so quiet, when compared with the exuberant choruses of spring. Molt of the flight feathers is the most highly organized part of the process. Some species, for example, begin by dropping the outermost primary feathers on each side (to retain balance in the air) and wait until the replacement feathers are about one-third grown before shedding the next outermost, and so on. Others always start with the innermost primary feathers and work outward. Yet other species begin in the middle and work outward on both sides. Most ducks shed their wing feathers at once, and remain flightless for two or three weeks while the replacement feathers grow.

The ever-watchful plover can detect a possible threat at a considerable distance. When she does, the nesting bird moves inconspicuously off the nest to a spot well away from eggs or chicks. At this point she may use one of several ploys. One technique involves first moving quietly toward an approaching animal and then setting off noisily through the grass or brush in a low, crouching run away from the nest, while emitting rodent like squeaks. The effect mimics a scurrying mouse or vole, and the behavior rivets the attention of the type of predators that would also be interested in eggs and chicks. Another deception begins with quiet movement to an exposed and visible location well away from the nest. Once there, the bird pretends to incubate a brood. When the predator approaches, the parent flees, leaving the false nest to be searched. The direction in which the plover "escapes" is such that if the predator chooses to follow, it will be led still further away from the true nest. The plover's most famous stratagem is the broken-wing display, actually a continuum of injury-mimicking behaviors spanning the range from slight disability to near-complete helplessness. One or both wings are held in an abnormal position, suggesting injury. The bird appears to be attempting escape along an irregular route that indicates panic. In the most extreme version of the display, the bird flaps one wing in an apparent attempt to take to the air, flops over helplessly, struggles back to its feet, runs away a short distance, seemingly attempts once more to take off, flops over again as the "useless" wing fails to provide any lift, and so on. Few predators fail to pursue such obviously vulnerable prey. Needless to say, each short run between "flight attempts" is directed away from the nest.

PASSAGE 63 The most thoroughly studied cases of deception strategies employed by ground-nesting birds involve plovers, small birds that typically nest on beaches or in open fields, their nests merely scrapes in the sand or earth. Plovers also have an effective repertoire of tricks for distracting potential nest predators from their exposed and defenseless eggs or chicks.

PASSAGE 64 What unusual or unique biological trait led to the remarkable diversification and unchallenged success of the ants for ever 50 million years? The answer appears to be that they were the first group of predatory eusocial insects that both lived and foraged

primarily in the soil and in rotting vegetation on the ground. Eusocial refers to a form of insect society characterized by specialization of tasks and cooperative care of the young; it is rare among insects. Richly organized colonies of the land made possible by eusociality enjoy several key advantages over solitary individuals. Under most circumstances groups of workers are better able to forage for food and defend the nest, because they can switch from individual to group response and back again swiftly and according to need. When a food object or nest intruder is too large for one individual to handle, nestmates can be quickly assembled by alarm or recruitment signals. Equally important is the fact that the execution of multiple-step tasks is accomplished in a series-parallel sequence. That is, individual ants can specialize in particular steps, moving from one object (such as a larva to be fed) to another (a second larva to be fed). They do not need to carry each task to completion from start to finish — for example, to check the larva first, then collect the food, then feed the larva. Hence, if each link in the chain has many workers in attendance, a series directed at any particular object is less likely to fail. Moreover, ants specializing in particular labor categories typically constitute a caste specialized by age or body form or both. There has been some documentation of the superiority in performance and net energetic yield of various castes for their modal tasks, although careful experimental studies are still relatively few. What makes ants unusual in the company of eusocial insects is the fact that they are the only eusocial predators (predators are animals that capture and feed on other animals) occupying the soil and ground litter. The eusocial termites live in the same places as ants and also have wingless workers, but they feed almost exclusively on dead vegetation.

At the heart of a comet's coma lies a nucleus of solid material, typically no more than 10 kilometers across. The visible coma is a huge cloud of gas and dust that has escaped from the nucleus, which then surrounds like an extended atmosphere. The coma can extend as far as a million kilometers outward from the nucleus. Around the coma there is often an even larger invisible envelope of hydrogen gas. The most graphic proof that the grand spectacle of a comet develops from a relatively small and inconspicuous chunk of ice and dust was the close-up image obtained in 1986 by the European Giotto probe of the nucleus of Halley's Comet. It turned out to be a bit like a very dark asteroid, measuring 16 by 8 kilometers. Ices have evaporated from its outer layers to leave a crust of nearly black dust all over the surface. Bright jets of gas from evaporating ice burst out on the side facing the Sun, where the surface gets heated up, carrying dust with them. This is how the coma and the tails are created. Comets grow tails only when they get warm enough for ice and dust to boil off. As a comet's orbit brings it closer to the sun, first the coma grows, then two distinct tails usually form. One, the less common kind, contains electrically charged (i.e., ionized) atoms of gas, which are blown off directly in the direction away from the Sun by the magnetic field of the solar wind. The other tail is made of neutral dust particles, which get gently pushed back by the pressure of the sunlight itself. Unlike the ion tail, which is straight, the dust tail becomes curved as the particles follow their own orbits around the Sun.

PASSAGE 65 No two comets ever look identical, but they have basic features in common, one of the most obvious of which is a coma. A coma looks like a misty, patch of light with one or more tails often streaming from it in the direction away from the sun.

PASSAGE 66 Long before they can actually speak, babies pay special attention to the speech they

hear around them. Within the first month of their lives, babies' responses to the sound of the human voice will be different from their responses to other sorts of auditory stimuli. They will stop crying when they hear a person talking, but not if they hear a bell or the sound of a rattle. At first, the sounds that an infant notices might be only those words that receive the heaviest emphasis and that often occur at the ends of utterances. By the time they are six or seven weeks old, babies can detect the difference between syllables pronounced with rising and falling inflections. Very soon, these differences in adult stress and intonation can influence babies' emotional states and behavior. Long before they develop actual language comprehension, babies can sense when an adult is playful or angry, attempting to initiate or terminate new behavior, and so on, merely on the basis of cues such as the rate, volume, and melody of adult speech. Adults make it as easy as they can for babies to pick up a language by exaggerating such cues. One researcher observed babies and their mothers in six diverse cultures and found that, in all six languages, the mothers used simplified syntax, short utterances and nonsense sounds, and transformed certain sounds into baby talk. Other investigators have noted that when mothers talk to babies who are only a few months old, they exaggerate the pitch, loudness, and intensity of their words. They also exaggerate their facial expressions, hold vowels longer, and emphasize certain words. More significant for language development than their response to general intonation is observation that tiny babies can make relatively fine distinctions between speech sounds. In other words, babies enter the world with the ability to make precisely those perceptual discriminations that are necessary if they are to acquire aural language. Babies obviously derive pleasure from sound input, too: even as young as nine months they will listen to songs or stories, although the words themselves are beyond their understanding. For babies, language is a sensory-motor delight rather than the route to prosaic meaning that it often is for adults.

and aspect, or attitude to the Sun. Florida's ancient scrub demonstrates this principle. Its soil is pure silica, so barren it supports only lichens as ground cover. It does, however, sustain a sand-swimming lizard that cannot live where there is moisture or plant matter the soil. Its climate, despite more than 50 inches of annual rainfall, is blistering desert. The only plant life it can sustain is the xerophytic, the quintessentially dry. Its altitude is a mere couple of hundred feet, but it is high ground on a peninsula elsewhere close to sea level, and its drainage is so critical that a difference of inches in elevation can bring major changes in its plant communities. Its aspect is flat direct, brutal — and subtropical. Florida's surrounding lushness cannot impinge on its desert scrubbiness. This does not sound like an attractive place. It does not look much like one either: shrubby little oaks, clumps of scraggly bushes prickly pear, thorns, and tangles. "It appears," Said one early naturalist, "to desire to display the result of the misery through which it has passed and is passing". By our narrow standards, scrub is not beautiful; neither does it meet our selfish utilitarian needs. Even the name is an epithet, a synonym for the stunted, the scruffy, the insignificant, what is beautiful about such a place? The most important remaining patches of scrub lie along the Lake Wales Ridge, a chain of paleoislands running for a hundred miles down the center of Florida, in most places less than ten miles wide. It is relict seashore, tossed up millions of years ago when ocean levels were higher and the rest of the peninsula was submerged. That ancient emergence is precisely what makes Lake Wales Ridge so precious: it has remained unsubmerged, its ecosystems essentially undisturbed since the Miocene era. As a result, it has gathered to itself one of the largest collections of rare organisms in the world. Only about 75 plant species survive there, but at least 30 of these are found nowhere else on Earth.

PASSAGE 67 Geographers say that what defines a place are four properties: soil, climate, altitude,


In the North American colonies, red ware, a simple pottery fired at low temperatures, and stone ware, a strong, impervious grey pottery fired at high temperatures, were produced from two different native clays. These kinds of pottery were produced to supplement imported European pottery. When the American Revolution (1775-1783) interrupted the flow of the superior European ware, there was incentive for American potters to replace the imports with comparable domestic goods. Stoneware, which had been simple, utilitarian kitchenware, grew increasingly ornate throughout the nineteenth century, and in addition to the earlier scratched and drawn designs, three-dimensional molded relief decoration became popular. Representational motifs largely replaced the earlier abstract decorations. Birds and flowers were particularly evident, but other subjects — lions, flags, and clipper ships — are found. Some figurines, mainly of dogs and lions, were made in this medium. Sometimes a name, usually that of the potter, was die-stamped onto a piece. As more and more large kilns were built to create the high-fired stoneware, experiments revealed that the same clay used to produce low-fired red ware could produce a stronger, paler pottery if fired at a hotter temperature. The result was yellow ware, used largely for serviceable items; but a further development was Rockingham ware — one of the most important American ceramics of the nineteenth century. (The name of the ware was probably derived from its resemblance to English brown-glazed earthenware made in South Yorkshire.) It was created by adding a brown glaze to the fired clay, usually giving the finished product a mottled appearance. Various methods of spattering or sponging the glaze onto the ware account for the extremely wide variations in color and add to the interest of collecting Rockingham. An advanced form of Rockingham was flint enamel, created by dusting metallic powders onto the Rockingham glaze to produce brilliant varicolored streaks. Articles for nearly every household activity and ornament could be bought in Rockingham ware: dishes and bowls, of course; also bedpans, foot warmers, cuspidors, lamp bases, doorknobs, molds, picture frames, even curtain tiebacks. All these items are highly collectible today and are eagerly sought. A few Rockingham specialties command particular affection among collectors and correspondingly high prices.

Newspaper publishers in the United States have long been enthusiastic users and distributors of weather maps. Although some newspapers that had carried the United States Weather Bureau's national weather map in 1912 dropped it once the novelty had passed, many continued to print the daily weather chart provided by their local forecasting office. In the 1930's, when interest in aviation and progress in air-mass analysis made weather patterns more newsworthy, additional newspapers started or resumed the daily weather map. In 1935, The Associated Press (AP) news service inaugurated its WirePhoto network and offered subscribing newspapers morning and afternoon weather maps redrafted by the AP's Washington, B.C., office from charts provided by the government agency. Another news service, United Press International (UPI), developed a competing Photowire network and also provided timely weather maps for both morning and afternoon newspapers. After the United States government launched a series of weather satellites in 1966, both the AP and UPI offered cloud-cover photos obtained from the Weather Bureau. In the late 1970's and early 1980's, the weather map became an essential ingredient in the redesign of the American newspaper. News publishers, threatened by increased competition from television for readers' attention, sought to package the news more conveniently and attractively. In 1982, many publishers felt threatened by the new USA Today, a national daily newspaper that used a page-wide, full-color weather map as its key design element. That the weather map in USA Today did not include information about weather fronts and pressures attests to the largely symbolic role it played. Nonetheless, competing local and metropolitan newspapers responded in a variety of ways. Most substituted full-color temperature maps for the standard weather maps, while others dropped the comparatively drab satellite photos or added regional forecast maps with pictorial symbols to indicate rainy, snowy, cloudy, or clear conditions. A few newspapers, notably The New York Times, adopted a highly informative yet less visually prominent weather map that was specially designed to explain an important recent or imminent weather event. Ironically, a newspaper's richest, most instructive weather maps often are comparatively small and inconspicuous.



The origins of nest-building remain obscure, but current observations of nest-building activities provide evidence of their evolution. Clues to this evolutionary process can be found in the activities of play and in the behavior and movements of birds during mating, such as incessant pulling at strips of vegetation or scraping of the soil. During the early days of the reproductive cycle, the birds seem only to play with the building materials. In preparation for mating, they engage in activities that resemble nest-building, and continue these activities throughout and even after the mating cycle. Effective attempts at construction occur only after mating. Although nest-building is an instinctive ability, there is considerable adaptability in both site selection and use of materials, especially with those species which build quite elaborate constructions. Furthermore, some element of learning is often evident since younger birds do not build as well as their practiced elders. Young ravens, for example, first attempt to build with sticks of quite unsuitable size, while a jackdaw's first nest includes virtually any movable object. The novelist John Steinbeck recorded the contents of a young osprey nest built in his garden, which included three shirts, a bath towel, and one arrow. Birds also display remarkable behavior in collecting building materials. Crows have been seen to tear off stout green twigs, and sparrowhawks will dive purposefully onto a branch until it snaps and then hang upside down to break it off. Golden eagles, over generations of work, construct enormous nests. One of these, examined after it had been dislodged by high winds, weighed almost two tons and included foundation branches almost two meters long. The carrying capacity of the eagles, however, is only relative to their size and most birds are able to carry an extra load of just over twenty percent of their body weight.

Cities develop as a result of functions that they can perform. Some functions result directly from the ingenuity of the citizenry, but most functions result from the needs of the local area and of the surrounding hinterland (the region that supplies goods to the city and to which the city furnishes services and other goods). Geographers often make a distinction between the situation and the site of a city. Situation refers to the general position in relation to the surrounding region, whereas site involves physical characteristics of the specific location. Situation is normally much more important to the continuing prosperity of a city. If a city is well situated in regard to its hinterland, its development is much more likely to continue. Chicago, for example, possesses an almost unparalleled situation: it is located at the southern end of a huge lake that forces east-west transportation lines to be compressed into its vicinity, and at a meeting of significant land and water transport routes. It also overlooks what is one of the world's finest large farming regions. These factors ensured that Chicago would become a great city regardless of the disadvantageous characteristics of the available site, such as being prone to flooding during thunderstorm activity. Similarly, it can be argued that much of New York City's importance stems from its early and continuing advantage of situation. Philadelphia and Boston both originated at about the same time as New York and shared New York's location at the western end of one of the world's most important oceanic trade routes, but only New York possesses an easy-access functional connection (the Hudson-Mohawk lowland) to the vast Midwestern hinterland. This account does not alone explain New York's primacy, but it does include several important factors. Among the many aspects of situation that help to explain why some cities grow and others do not, original location on a navigable waterway seems particularly applicable. Of course, such characteristic as slope, drainage, power resources, river crossings, coastal shapes, and other physical characteristics help to determine city location, but such factors are normally more significant in early stages of city development than later.



The Harlem Renaissance, a movement of the 1920's, marked the twentieth century's first period of intense activity by African Americans in the field of literature, art, and music in the United States. The philosophy of the movement combined realism, ethnic consciousness, and Americanism. Encouraged by the example of certain Americans of European descent such as Thomas Eakins, Robert Henri, and George Luks, who had included persons of African descent in their paintings as serious studies rather than as trivial or sentimental stereotypes, African American artists of this period set about creating a new portrayal of themselves and their lives in the United States. As they began to strive for social and cultural independence. Their attitudes toward themselves changed, and, to some extent, other segments of American society began to change their attitudes toward them. Thus, though the Harlem Renaissance was a short-lived movement, its impact on American art and culture continues to the present. The district in New York City known as Harlem was the capital of the movement. In 1925 an issue of Survey Graphic magazine devoted exclusively to Harlem and edited by philosopher Alain Locke became the manifesto of the African American artistic movement. Locke strongly suggested that individuals, while accepting their Americanism, take pride in their African ancestral arts and urged artists to look to Africa for substance and inspiration. Far from advocating a withdrawal from American culture, as did some of his contemporaries, Locke recommended a cultural pluralism through which artists could enrich the culture of America. African Americans were urged by Locke to be collaborators and participators with other Americans in art, literature, and music; and at the same time to preserve, enhance, and promote their own cultural heritage. Artists and intellectuals from many parts of the United States and the Caribbean had been attracted to Harlem by the pulse and beat of its unique and dynamic culture. From this unity created by the convergence of artists from various social and geographical backgrounds came a new spirit, which, particularly in densely populated Harlem, was to result in greater group awareness and self-determination. African American graphic artists took their place beside the poets and writers of the Harlem Renaissance and carried on efforts to increase and promote the visual arts.

PASSAGE 73 The interrelationship of science, technology, and industry is taken for granted today — summed up, not altogether accurately, as "research and development." Yet historically this widespread faith in the economic virtues of science is a relatively recent phenomenon, dating back in the United States about 150 years, and in the Western world as a whole not over 300 years at most. Even in this current era of large scale, intensive research and development, the interrelationships involved in this process are frequently misunderstood. Until the coming of the Industrial Revolution, science and technology evolved for the most part independently of each other. Then as industrialization became increasingly complicated, the craft techniques of preindustrial society gradually gave way to a technology based on the systematic application of scientific knowledge and scientific methods. This changeover started slowly and progressed unevenly. Until late in the nineteenth century, only a few industries could use scientific techniques or cared about using them. The list expanded noticeably after 1870, but even then much of what passed for the application of science was "engineering science" rather than basic science. Nevertheless, by the middle of the nineteenth century, the rapid expansion of scientific knowledge and of public awareness — if not understanding — of it had created a belief that the advance of science would in some unspecified manner automatically generate economic benefits. The widespread and usually uncritical acceptance of this thesis led in turn to the assumption that the application of science to industrial purposes was a linear process, starting with fundamental science, then proceeding to applied science or technology, and through them to industrial use. This is probably the most common pattern, but it is not invariable. New areas of science have been opened up and fundamental discoveries made as a result of attempts to solve a specific technical or economic problem. Conversely, scientists who mainly do basic research also serve as consultants on projects that apply research in practical ways. In sum, the science-technology-industry relationship may flow in several different ways, and the particular channel it will follow depends on the individual situation. It may at times even be multidirectional.

PASSAGE 74 Glaciers are large masses of ice on land that show evidence of past or present movement. They grow by the gradual transformation of snow into glacier ice. A fresh snowfall is a fluffy mass of loosely packed snowflakes, small delicate ice crystals grown in the atmosphere. As the snow ages on the ground for weeks or months, the crystals shrink and become more compact, and the whole mass becomes squeezed together into a more dense form, granular snow. As new snow falls and buries the older snow, the layers of granular snow further compact to form firm, a much denser kind of snow, usually a year or more old, which has little pore space. Further burial and slow cementation — a process by which crystals become bound together in a mosaic of intergrown ice crystals — finally produce solid glacial ice. In this process of recrystallization, the growth of new crystals at the expense of old ones, the percentage of air is reduced from about 90 percent for snowflakes to less than 20 percent for glacier ice. The whole process may take as little as a few years, but more likely ten or twenty years or longer. The snow is usually many meters deep by the time the lower layers are converted into ice. In cold glaciers those formed in the coldest regions of the Earth, the entire mass of ice is at temperatures below the melting point and no free water exists. In temperate glaciers, the ice is at the melting point at every pressure level within the glacier, and free water is present as small drops or as larger accumulations in tunnels within or beneath the ice. Formation of a glacier is complete when ice has accumulated to a thickness (and thus weight) sufficient to make it move slowly under pressure, in much the same way that solid rock deep within the Earth can change shape without breaking. Once that point is reached, the ice flows downhill, either as a tongue of ice filling a valley or as thick ice cap that flows out in directions from the highest central area where the most snow accumulates. The trip down leads to the eventual melting of ice.

PASSAGE 75 Many prehistoric people subsisted as hunters and gatherers. Undoubtedly, game animals, including some very large species, provided major components of human diets. An important controversy centering on the question of human effects on prehistoric wildlife concerns the sudden disappearance of so many species of large animals at or near the end of the Pleistocene epoch. Most paleontologists suspect that abrupt changes in climate led to the mass extinctions. Others, however, have concluded that prehistoric people drove many of those species to extinction through overhunting. In their "Pleistocene overkill hypothesis," they cite what seems to be a remarkable coincidence between the arrival of prehistoric peoples in North and South America and the time during which mammoths, giant ground sloths, the giant bison, and numerous other large mammals became extinct. Perhaps the human species was driving others to extinction long before the dawn of history. Hunter-gatherers may have contributed to Pleistocene extinctions in more indirect ways. Besides overhunting, at least three other kinds of effects have been suggested: direct competition, imbalances between competing species of game animals, and early agricultural practices. Direct competition may have brought about the demise of large carnivores such as the saber-toothed cats. These animals simply may have been unable to compete with the increasingly sophisticated hunting skills of Pleistocene people. Human hunters could have caused imbalances among game animals, leading to the extinctions of species less able to compete. When other predators such as the gray wolf prey upon large mammals, they generally take high proportions of each year's crop of young. Some human hunters, in contrast, tend to take the various age-groups of large animals in proportion to their actual occurrence. If such hunters first competed with the larger predators and then replaced them, they may have allowed more young to survive each year, gradually increasing the populations of favored species. As these populations expanded, they in turn may have competed with other game species for the same environmental niche, forcing the less hunted species into extinction. This theory, suggests that human hunters played an indirect role in Pleistocene extinctions by hunting one species more than another.

PASSAGE 76 Under the Earth's topsoil, at various levels, sometimes under a layer of rock, there are deposits of clay. Look at cuts where highways have been built to see exposed clay beds; or look at a construction site, where pockets of clay may be exposed. Rivers also reveal clay along their banks, and erosion on a hillside may make clay easily accessible. What is clay made of? The Earth's surface is basically rock, and it is this rock that gradually decomposes into clay. Rain, streams, alternating freezing and thawing, roots of trees and plants forcing their way into cracks, earthquakes, volcanic action, and glaciers — all of these forces slowly break down the Earth's exposed rocky crust into smaller and smaller pieces that eventually become clay. Rocks are composed of elements and compounds of elements. Feldspar, which is the most abundant mineral on the Earth's surface, is basically made up of the oxides silica and alumina combined with alkalis like potassium and some so-called impurities such as iron. Feldspar is an essential component of granite rocks, and as such it is the basis of clay. When it is wet, clay can be easily shaped to make a variety of useful objects, which can then be fired to varying degrees of hardness and covered with impermeable decorative coatings of glasslike material called glaze. Just as volcanic action, with its intense heat, fuses the elements in certain rocks into a glasslike rock called obsidian, so can we apply heat to earthen materials and change them into a hard, dense material. Different clays need different heat levels to fuse, and some, the low-fire clays, never become nonporous and watertight like highly fired stoneware. Each clay can stand only a certain amount of heat without losing its shape through sagging or melting. Variations of clay composition and the temperatures at which they are fired account for the differences in texture and appearance between a china teacup and an earthenware flowerpot.

PASSAGE 77 It is estimated that over 99 percent of all species that ever existed have become extinct. What causes extinction? When a species is no longer adapted to a changed environment, it may perish. The exact causes of a species' death vary from situation to situation. Rapid ecological change may render an environment hostile to a species. For example, temperatures may change and a species may not be able to adapt. Food resources may be affected by environmental changes, which will then cause problems for a species requiring these resources. Other species may become better adapted to an environment, resulting in competition and, ultimately, in the death of a species. The fossil record reveals that extinction has occurred throughout the history of Earth. Recent analyses have also revealed that on some occasions many species became extinct at the same time — a mass extinction. One of the best-known examples of mass extinction occurred 65 million years ago with the demise of dinosaurs and many other forms of life. Perhaps the largest mass extinction was the one that occurred 225 million years ago, when approximately 95 percent of all species died, mass extinctions can be caused by a relatively rapid change in the environment and can be worsened by the close interrelationship of many species. If, for example, something were to happen to destroy much of the plankton in the oceans, then the oxygen content of Earth would drop, affection even organisms not living in the oceans. Such a change would probably lead to a mass extinction. One interesting, and controversial, finding is that extinctions during the past 250 million years have tended to be more intense every 26 million years. This periodic extinction might be due to intersection of the Earth's orbit with a cloud of comets, but this theory is purely speculative. Some researchers have also speculated that extinction may often be random. That is, certain species may be eliminated and others may survive for no particular reason. A species' survival may have nothing to do with its ability or inability to adapt. If so, some of evolutionary history may reflect a sequence of essentially random events.

PASSAGE 78 Archaeological discoveries have led some scholars to believe that the first Mesopotamian inventors of writing may have been a people the later Babylonians called Subarians. According to tradition, they came from the north and moved into Uruk in the south. By about 3100 B.C., they were apparently subjugated in southern Mesopotamia by the Sumerians, whose name became synonymous with the region immediately north of the Persian Gulf, in the fertile lower valleys of the Tigris and Euphrates. Here the Sumerians were already well established by the year 3000 B.C. They had invented bronze, an alloy that could be cast in molds, out of which they made tools and weapons. They lived in cities, and they had begun to acquire and use capital. Perhaps most important, the Sumerians adapted writing (probably from the Subarians) into a flexible tool of communication. Archaeologists have known about the Sumerians for over 150 years. Archaeologists working at Nineveh in northern Mesopotamia in the mid-nineteenth century found many inscribed clay tablets. Some they could decipher because the language was a Semitic one (Akkadian), on which scholars had already been working for a generation. But other tablets were inscribed in another language that was not Semitic and previously unknown. Because these inscriptions made reference to the king of Sumer and Akkad, a scholar suggested that the new language be called Sumerian. But it was not until the 1890's that archaeologists excavating in city-states well to the south of Nineveh found many thousands of tablets inscribed in Sumerian only. Because the Akkadians thought of Sumerian as a classical language (as ancient Greek and Latin are considered today), they taught it to educated persons and they inscribed vocabulary, translation exercises, and other study aids on tablets. Working from known Akkadian to previously unknown Sumerian, scholars since the 1890's have learned how to read the Sumerian language moderately well. Vast quantities of tablets in Sumerian have been unearthed during the intervening years from numerous sites.

PASSAGE 79 Some animal behaviorists argue that certain animals can remember past events, anticipate future ones, make plans and choices, and coordinate activities within a group. These scientists, however, are cautious about the extent to which animals can be credited with conscious processing. Explanations of animal behavior that leave out any sort of consciousness at all and ascribe actions entirely to instinct leave many questions unanswered. One example of such unexplained behavior: honeybees communicate the sources of nectar to one another by doing a dance in a figure-eight pattern. The orientation of the dance conveys the position of the food relative to the sun's position in the sky, and the speed of the dance tells how far the food source is from the hive. Most researchers assume that the ability to perform and encode the dance is innate and shows no special intelligence. But in one study, when experimenters kept changing the site of the food source, each time moving the food 25 percent farther from the previous site, foraging honeybees began to anticipate where the food source would appear next. When the researchers arrived at the new location, they would find the bees circling the spot, waiting for their food. No one has yet explained how bees, whose brains weigh four ten-thousandths of an ounce, could have inferred the location of the new site. Other behaviors that may indicate some cognition include tool use. Many animals, like the otter who uses a stone to crack mussel shells, are capable of using objects in the natural environment as rudimentary tools. One researcher has found that mother chimpanzees occasionally show their young how to use tools to open hard nuts. In one study, chimpanzees compared two pairs of food wells containing chocolate chips. One pair might contain, say, five chips and three chips, the other four chips and three chips. Allowed to choose which pair they wanted, the chimpanzees almost always chose the one with the higher total, showing some sort of summing ability. Other chimpanzees have learned to use numerals to label quantities of items and do simple sums.

PASSAGE 80 A survey is a study, generally in the form of an interview or a questionnaire that provides information concerning how people think and act. In the United States, the best-known surveys are the Gallup poll and the Harris poll. As anyone who watches the news during presidential campaigns knows, these polls have become an important part of political life in the United States. North Americans are familiar with the many person-on-the-street interviews on local television news shows. While such interviews can be highly entertaining, they are not necessarily an accurate indication of public opinion. First, they reflect the opinions of only those people who appear at a certain location. Thus, such samples can be biased in favor of commuters, middle-class shoppers, or factory workers, depending on which area the newspeople select. Second, television interviews tend to attract outgoing people who are willing to appear on the air, while they frighten away others who may feel intimidated by a camera. A survey must be based on a precise, representative sampling if it is to genuinely reflect a broad range of the population. In preparing to conduct a survey, sociologists must exercise great care in the wording of questions. An effective survey question must be simple and clear enough for people to understand it. It must also be specific enough so that there are no problems in interpreting the results. Even questions that are less structured must be carefully phrased in order to elicit the type of information desired. Surveys can be indispensable sources of information, but only if the sampling is done properly and the questions are worded accurately. There are two main forms of surveys: the interview and the questionnaire. Each of these forms of survey research has its advantages. An interviewer can obtain a high response rate because people find it more difficult to turn down a personal request for an interview than to throw away a written questionnaire. In addition, an interviewer can go beyond written questions and probe for a subject's underlying feelings and reasons. However, questionnaires have the advantage of being cheaper and more consistent.

PASSAGE 81 The largest of the giant gas planets, Jupiter, with a volume 1,300 times greater than Earth's, contains more than twice the mass of all the other planets combined. It is thought to be a gaseous and fluid planet without solid surfaces, Had it been somewhat more massive, Jupiter might have attained internal temperatures as high as the ignition point for nuclear reactions, and it would have flamed as a star in its own right. Jupiter and the other giant planets are of a low-density type quite distinct from the terrestrial planets: they are composed predominantly of such substances as hydrogen, helium, ammonia, and methane, unlike terrestrial planets. Much of Jupiter's interior might be in the form of liquid, metallic hydrogen. Normally, hydrogen is a gas, but under pressures of millions of kilograms per square centimeter, which exist in the deep interior of Jupiter, the hydrogen atoms might lock together to form a liquid with the properties of a metal. Some scientists believe that the innermost core of Jupiter might be rocky, or metallic like the core of Earth. Jupiter rotates very fast, once every 9.8 hours. As a result, its clouds, which are composed largely of frozen and liquid ammonia, have been whipped into alternating dark and bright bands that circle the planet at different speeds in different latitudes. Jupiter's puzzling Great Red Spot changes size as it hovers in the Southern Hemisphere. Scientists speculate it might be a gigantic hurricane, which because of its large size (the Earth could easily fit inside it), lasts for hundreds of years. Jupiter gives off twice as much heat as it receives from the Sun. Perhaps this is primeval heat or heat generated by the continued gravitational contraction of the planet. Another starlike characteristic of Jupiter is its sixteen natural satellites, which, like a miniature model of the Solar System, decrease in density with distance — from rocky moons close to Jupiter to icy moons farther away. If Jupiter were about 70 times more massive, it would have become a star, Jupiter is the best-preserved sample of the early solar nebula, and with its satellites, might contain the most important clues about the origin of the Solar System.

stimulation and affection necessary for healthy growth. The development of attachment in human infants is a lengthy process involving changes in psychological structures that lead to a deep affectional tie between parent and baby.

PASSAGE 82 Ethology is concerned with the study of adaptive, or survival, value of behavior and its evolutionary history. Ethological theory began to be applied to research on children in the 1960's but has become even more influential today. The origins of ethology can be traced back to the work of Darwin. Its modern foundations were laid by two European zoologists, Konrad Lorenz and Niko Tinbergen. Watching the behaviors diverse animal species in their natural habitats, Lorenz, and Tinbergen observed behavior patterns that promote survival. The most well-known of these is imprinting, the early following behavior of certain baby birds that ensures that the young will stay close to their mother and be fed and protected from danger. Imprinting takes place during an early, restricted time period of development. If the mother goose is not present during this time, but an object resembling her in important features is, young goslings may imprint on it instead. Observations of imprinting led to major concept that has been applied in child development — the critical period. It refers to a limited times span during which the child is biologically prepared to acquire certain adaptive behaviors but needs the support of suitably stimulating environment. Many researchers have conducted studies to find out whether complex cognitive and social behaviors must be learned during restricted time periods. For example, if children are deprived of adequate food or physical and social stimulation during the early years of life, will their intelligence be permanently impaired? If language is not mastered during the preschool years, is the child's capacity to acquire it reduced? Inspired by observations of imprinting, in 1969 the British psychoanalyst John Bowlby applied ethological theory to the understanding of the relationship between an infant and its parents. He argued that attachment behaviors of babies, such as smiling, babbling, grasping, and crying, are built-in social signals that encourage the parents to approach, care for, and interact with the baby. By keeping a parent near, these behaviors help ensure that the baby will be fed, protected from danger, and provided with the

PASSAGE 83 The economic depression in the late-nineteenth-century United States contributed significantly to a growing movement in literature toward realism and naturalism. After the 1870's, a number of important authors began to reject the romanticism that had prevailed immediately following the Civil War of 1861-1865 and turned instead to realism. Determined to portray life as it was, with fidelity to real life and accurate representation without idealization, they studied local dialects, wrote stories which focused on life in specific regions of the country, and emphasized the "true" relationships between people. In doing so, they reflected broader trends in the society, such as industrialization, evolutionary theory which emphasized the effect of the environment on humans, and the influence of science. Realists such as Joel Chandler Harris and Ellen Glasgow depicted life in the South, Hamlin Garland described life on the Great Plains, and Sarah Orne Jewett wrote about everyday life in rural New England. Another realist, Bret Harte, achieved fame with stories that portrayed local life in the California mining camps. Samuel Clemens, who adopted the pen name Mark Twain, became the country's most outstanding realist author, observing life around him with a humorous and skeptical eye. In his stories and novels, Twain drew on his own experiences and used dialect and common speech instead of literary language, touching off a major change in American prose style. Other writers became impatient even with realism. Pushing evolutionary theory to its limits, they wrote of a world in which a cruel and merciless environment determined human fate. These writers, called naturalists, often focused on economic hardship, studying people struggling with poverty, and other aspects of urban and industrial life. Naturalists brought to their writing a passion for direct and honest experience. Theodore Dreiser, the foremost naturalist writer, in novels such as Sister Carrie, grimly portrayed a dark world in which human beings were tossed about by forces beyond their understanding or control. Dreiser thought that writers should tell the truth

about human affairs, not fabricate romance, and Sister Carrie, he said, was "not intended as a piece of literary craftsmanship, but was a picture of conditions."

information pertained to the locale in which they would be used.

PASSAGE 84 The lack of printing regulations and the unenforceability of British copyright law in the American colonies made it possible for colonial printers occasionally to act as publishers. Although they rarely undertook major publishing project because it was difficult to sell books as cheaply as they could be imported from Europe, printers in Philadelphia did publish work that required only small amounts of capital, paper, and type. Broadsides could be published with minimal financial risk. Consisting of only one sheet of paper and requiring small amounts of type, broadsides involved lower investments of capital than longer works. Furthermore, the broadside format lent itself to subjects of high, if temporary, interest, enabling them to meet with ready sale. If the broadside printer miscalculated, however, and produced a sheet that did not sell, it was not likely to be a major loss, and the printer would know this immediately, There would be no agonizing wait with large amounts of capital tied up, books gathering dust on the shelves, and creditors impatient for payment. In addition to broadsides, books and pamphlets, consisting mainly of political tracts, catechisms, primers, and chapbooks were relatively inexpensive to print and to buy. Chapbooks were pamphlet-sized books, usually containing popular tales, ballads, poems, short plays, and jokes, small, both in formal and number of pages, they were generally bound simply, in boards (a form of cardboard) or merely stitched in paper wrappers (a sewn antecedent of modern-day paperbacks). Pamphlets and chapbooks did not require fine paper or a great deal of type to produce they could thus be printed in large, cost-effective editions and sold cheaply. By far, the most appealing publishing investments were to be found in small books that had proven to be steady sellers, providing a reasonably reliable source of income for the publisher. They would not, by nature, be highly topical or political, as such publications would prove of fleeting interest. Almanacs, annual publications that contained information on astronomy and weather patterns arranged according to the days, week, and months of a given year, provided the perfect steady seller because their

PASSAGE 85 Tulips are Old World, rather than New World, plants, with the origins of the species lying in Central Asia. They became an integral part of the gardens of the Ottoman Empire from the sixteenth century onward, and, soon after, part of European life as well. Holland, in particular, became famous for its cultivation of the flower. A tenuous line marked the advance of the tulip to the New World, where it was unknown in the wild. The first Dutch colonies in North America had been established in New Netherlands by the Dutch West India Company in 1624, and one individual who settled in New Amsterdam (today's Manhattan section of New York City) in 1642 described the flowers that bravely colonized the settlers' gardens. They were the same flowers seen in Dutch still-life paintings of the time: crown imperials, roses, carnations, and of course tulips. They flourished in Pennsylvania too, where in 1698 William Penn received a report of John Tateham's "Great and Stately Palace," its garden full of tulips. By 1760, Boston newspapers were advertising 50 different kinds of mixed tulip "roots." But the length of the journey between Europe and North America created many difficulties. Thomas Hancock, an English settler, wrote thanking his plant supplier for a gift of some tulip bulbs from England, but his letter the following year grumbled that they were all dead. Tulips arrived in Holland, Michigan, with a later wave of early nineteenth-century Dutch immigrants who quickly colonized the plains of Michigan. Together with many other Dutch settlements, such as the one at Pella, Iowa, they established a regular demand for European plants. The demand was bravely met by a new kind of tulip entrepreneur, the traveling salesperson. One Dutchman, Hendrick van der Schoot, spent six months in 1849 traveling through the United States taking orders for tulip bulbs. While tulip bulbs were traveling from Europe to the United States to satisfy the nostalgic longings of homesick English and Dutch settlers, North American plants were traveling in the opposite direction. In England, the enthusiasm for American plants was one reason why tulips dropped out of fashion in the gardens of the rich and famous.

PASSAGE 86 The smooth operation of an ant colony depends on ten to twenty different signals, most of which are pheromones (chemical signals triggering behavioral responses). It is estimated that red fire ants employ at least twelve different chemical signals. The simplest of these is the carbon dioxide from the respiration of an ant cluster, a chemical that acts as a pheromone to promote aggregation. Workers move toward a source of carbon dioxide, resulting in solitary ants moving to join a group. At the other extreme, the most complex of the fire ants' signals is probably colony odor, by which the workers of a particular colony or nest identify another worker as local or foreign. Each ant nest has its own odor as a result of its location, history, and local food supply. The resident ants pick up this odor on their bodies, so that ants of the same species, but from different nests, have different colony odors. This allows ants to identify intruders and maintain colony integrity. Fire ants also make use of an alarm pheromone to alert workers to an emergency, and their scouts lay down a trail pheromone as a guide during mass migrations. A fire ant queen emits a chemical signal that identifies her to the colony's workers. They respond by scurrying to gather around her. The decomposing corpse of a dead ant also generates a signal, to which workers respond by eliminating the corpse from the nest. Ants provide examples of both public (accessible to other species) and private messages. One of their most important private messages concerns food, for a food source is worth keeping secret. Each species marks its trails with signals that are meaningless to others, so that an ant crossing a trail left by another ant species typically notices nothing. On the other hand, a secret signal to mark a dead body is unnecessary. Many kinds of ants perceive a natural decomposition product of dead insects as a signal to remove a corpse. If an outsider recognizes this message and moves the body, no harm is done.

PASSAGE 87 Because the low latitudes of the Earth, the areas near the equator, receive more heat than the latitudes near the poles, and because the nature of heat is to expand and move, heat is transported from the tropics to the middle and high latitudes. Some of this heat is moved by winds and some by ocean currents, and some gets stored in the atmosphere in the form of latent heat. The term "latent heat" refers to the energy that has to be used to convert liquid water to water vapor. We know that if we warm a pan of water on a stove, it will evaporate, or turn into vapor, faster than if it is allowed to sit at room temperature. We also know that if we hang wet clothes outside in the summertime they will dry faster than in winter, when temperatures are colder. The energy used in both cases to change liquid water to water vapor is supplied by heat — supplied by the stove in the first case and by the Sun in the latter case. This energy is not lost. It is stored in water vapor in the atmosphere as latent heat. Eventually, the water stored as vapor in the atmosphere will condense to liquid again, and the energy will be released to the atmosphere. In the atmosphere, a large portion of the Sun's incoming energy is used to evaporate water, primarily in the tropical oceans. Scientists have tried to quantify this proportion of the Sun's energy. By analyzing temperature, water vapor, and wind data around the globe, they have estimated the quantity to be about 90 watts per square meter, or nearly 30 percent of the Sun's energy. Once this latent heat is stored within the atmosphere, it can be transported, primarily to higher latitudes, by prevailing, large-scale winds. Or it can be transported vertically to higher levels in the atmosphere, where it forms clouds and subsequent storms, which then release the energy back to the atmosphere.

inorganic hard parts, composed mostly of calcium carbonate, that form the vast majority of unaltered fossils. Calcite and aragonite also contributed to a substantial number of fossils of certain organisms.

PASSAGE 88 Generally, in orde

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智课网 TOEFL 备考资料 托福阅读真题 100 篇汇总托福 阅读真题 100 篇为大家总结了历年的 托福考试 真题,小编希望备考托福的考生能够在 托福阅读 真题中 不断的...
暂无评价|0人阅读|0次下载|举报文档【100篇老托福听力SSS听后感_英语学习_外语学习_教育专区。智课网 TOEFL 备考资料 【100 篇老托福听力 SSS 听后感摘要:...
托福阅读文章出处【2016 年官网发布】摘要: 托福阅读文章出处 2016 年新托福阅读备考:模拟练习必不可少 新托福考试(简称 iBT)阅读部分考试时 间为 60-100 分钟,...
今天小编来接着为大家介绍托福阅读 TPO1 原文,托福阅读 TPO1 包含 3 篇文章...The highest plants in the world occur at around 6,100 meters on Makalu ...

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