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ZOÖLOGY in zoölogy as an introduction to medical studies. One impression that has gained wide currency should be corrected: viz., that the chief business of the zoölogist is to know the different kinds of animals and be able to name them. That is zoölogy of the past, but it has been replaced by a better kind. Attention has been directed from the external appearances of animals, as shape, color, differences in horns, hoofs etc., to their internal structure and life processes. An attempt is being made to analyze their vital activities and to determine their position in the history of the universe. An examination of the textbooks of a generation ago will show that emphasis was unifomly placed on the classification of animals. In this period, also, the collector for museums and the hunter naturalist were dominant types of zoölogists. It is quite true that students of zoölogy should not be drawn away from the fields, forests and streams; nevertheless, that which is best and strongest in modern zoölogy is being worked out in the laboratory by experiments and observations on a few forms. These studies, especially in the last half of the 19th century, are leading to large generalizations regarding the science of life, which should become known to all people of liberal culture.

Zoölogy as a science aims to give a picture of animal life on the globe; to consider its structure; to analyze its activities; to account for it by tracing its history in general and in detail; and to consider its relation to nature at large. The history of biology includes that of zoölogy, and the article on biology should be consulted, where a number of general considerations are entered upon that need not be repeated here.

The new way of looking at the animal world did not come all at once, but has been the result of growth. Knowledge regarding animal life has advanced by a series of steps, and its progress can be divided into a number of periods. The first of these is the period extending from the earliest writings about animals to the renaissance of science in the 16th century. Zoölogical study was cultivated among ancient peoples and reached its highest development in that period in the work of Aristotle, the Hellenic philosopher-naturalist, who lived from B. C. 384 to B. C. 322. He was a man of truly scientific mind and made many original observations on the structure and development of animal life. With him classification was based upon structure, but was of secondary importance. His successors did not reach the level of the great Father of Natural History, as he has been called. Their work more and more took the line of systematic classification of animals, and lost in observations on structure and development. Pliny the Elder (A. D. 23–79) is the next prominent naturalist of antiquity. That Roman general and teacher has been unduly praised as a zoölogist, for he merely was a poor compiler, who mixed borrowed facts, fancy and fabulous stories. He replaced the natural classification of Aristotle by a highly artificial arrangement of animals, according to their place of abode on land or in water or in air. It is noteworthy that nothing of importance was added to the work of Aristotle till the awakening of observation in the 16th century.

In the intervening period the intellectual life of mankind took a retrograde movement. Observations and inquiry into nature were discontinued and, in fact, were discouraged by intellectual leaders. This led to superstition in reference to the natural universe. But an awakening came, and it was an epoch of unusual importance when men began once more to observe and experiment and so to lay the foundations of modern science. The new intellectual movement was led in the 16th century by Galileo, Descartes and Vesalius. The work of Vesalius (1514–64) in anatomy had great influence upon the development of zoölogy. Progress in anatomy helped zoölogy by giving a knowledge of structure. At first structural studies mainly were on the higher animals nearest man. Afterwards they were extended to other forms, including the invertebrates, and were made broadly comparative.

At the revival of learning the influence of Aristotle was mainly on the systematic classification of animals. His works were translated and extended by Wotton (1492–1555), Gesner (1516–65), Aldrovandi (1522–1605) and others who produced ponderous Latin treatises on natural history. These men and their successors for about two hundred years have been called the encyclopedists. The work of Gesner was of fine quality, and marks the beginning of careful observation and description of animals.

Passing over the notable work of naturalists like Malpighi (1628–94), Leeuwenhoek (1632–1723) and Swammerdam (1637–80) in the 17th century, who worked on minute anatomy and brought the microscope into use, we come to the period characterized by the work of Ray (1628–1705), Linnæus (1707–78) and Buffon (1707–88). Ray laid the foundations upon which Linnæus built. The name of the latter probably is more widely known than that of any other naturalist. He was a man of prodigious industry, filled with a zeal for collecting and naming natural objects. He greatly extended the number of known animals and plants, but did little toward deepening the knowledge of animal life. His chief service was in systematizing the groups and introducing the method of naming