【正文】 ions and donations of art, in some cases passing up opportunities to strengthen its collections. Deaccessing or selling off works of art has taken on new importance because of the museum’s space problems. And increasingly, curators have been forced to juggle gallery space, rotating one masterpiece into public view while another is sent to storage.Despite the clear need for additional gallery and storage space, however, the museum has no plan, no plan to break out of its envelope in the next fifteen years, according to Philadelphia Museum of Art’s president.13 Skyscrapers and EnvironmentIn the late 1960’s, many people in North America turned their attention toenvironmental problems, and new steelandglass skyscrapers were widely criticized. Ecologists pointed out that a cluster of tall buildings in acity often overburdens public transportation and parking lot capacities.Skyscrapers are also lavish consumers, and wasters, of electric power. In one recent year, the addition of 17 million square feet of skyscraper office space in New York City raised the peak daily 　demand for electricity by 120,000 kilowattsenough to supply the entire city of Albany, New York, for a day.Glasswalled skyscrapers can be especially wasteful. The heat loss (or gain)through a wall of halfinch plate glass is more than ten times thatthrough a typical masonry wall filled with insulation board. To lessen thestrain on heating and airconditioning equipment, builders of skyscrapershave begun to use doubleglazed panels of glass, and reflective glassescoated with silver or gold mirror films that reduce glare as well as heatgain. However, mirrorwalled skyscrapers raise the temperature of thesurrounding air and affect neighboring buildings.Skyscrapers put a severe strain on a city’s sanitation facilities, too. Iffully occupied, the two World Trade Center towers in New York City would alone generate million gallons of raw sewage each yearas much as a city the size of Stanford, Connecticut , which has a population of more than 109, 000.　14 A Rare Fossil RecordThe preservation of embryos and juveniles is a rate occurrence in the fossil record. The tiny, delicate skeletons are usually scattered by scavengers or destroyed by weathering before they can be fossilized. Ichthyosaurs had a higher chance of being preserved than did terrestrial creatures because, as marine animals, they tended to live in environments less subject to erosion.Still, their fossilization required a suite of factors: a slow rate of decay of soft tissues, little scavenging by other animals, a lack of swiftcurrents and waves to jumble and carry away small bones, and fairly rapidburial. Given these factors, some areas have bee a treasury ofwellpreserved ichthyosaur fossils.The deposits at Holzmaden, Germany, present an interesting case foranalysis. The ichthyosaur remains are found in black, bituminous marineshales deposited about 190 million years ago. Over the years, thousands of specimens of marine reptiles, fish and invertebrates have been recovered from these rocks. The quality of preservation is outstanding, but what is even more impressive is the number of ichthyosaur fossils containing preserved embryos. Ichthyosaurs with embryos have been reported from 6 different levels of the shale in a small area around Holzmaden, suggesting that a specific site was used by large numbers of 　ichthyosaurs repeatedly over time. The embryos are quite advanced in their physical development。 they form an electrocardiogram, which a doctor can study to determine how well the heart is working. The brain, too, sends out brain waves of electricity, which can be recorded in anelectroencephalogram. The electric currents generated by most living cells are extremely small often so small that sensitive instruments are needed to record them. But in some animals, certain muscle cells have bee so specialized as electrical generators that they do not work as muscle cells at all. When large numbers of these cell are linked together, the effects can be astonishing.The electric eel is an amazing storage battery. It can seed a jolt of as　much as eight hundred volts of electricity through the water in which itlive. (An electric house current is only one hundred twenty volts.) As many as fourfifths of all the cells in the electric eel’s body are specialized for generating electricity, and the strength of the shock it can deliver corresponds roughly to length of its body.05 The Beginning of DramaThere are many theories about the beginning of drama in ancient Greece. The on most widely accepted today is based on the assumption that drama evolved from ritual. The argument for this view goes as follows. In the beginning, human beings viewed the natural forces of the worldeven the seasonal changesas unpredictable, and they sought through various means to control these unknown and feared powers. Those measures which appeared to bring the desired results were then retained and repeated until they hardened into fixed rituals. Eventually stories arose which explained or veiled the mysteries of the rites. As time passed some rituals were abandoned, but the stories, later called myths, persisted and provided material for art and drama.Those who believe that drama evolved out of ritual also argue that those rites contained the seed of theater because music, dance, masks, and costumes were almost always used, furthermore, a 　suitable site had to be provided for performances and when the entire munity did not participate, a clear division was usually made between the acting area and the auditorium. In addition, there were performers, and, since considerable importance was attached to avoiding mistakes in the enactment of rites, religious leaders usually assumed that task. Wearing masks and costumes, they often impersonated other people, animals, or supernatural beings, and mimed the desired effec