INTRODUCTION 



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tive study of the form and structure of the other animals and these 

 in turn are compared, finally, with the human anatomy. The dis- 

 section, observation, and study of the parts, form, and relationship 

 of parts of the digestive system of the cat would be a good example 

 of anatomical study. Galen, A.D. 131-201; Vesalius, 1514-1564; 

 Cuvier, 1769-1832. 



B. Histology or Microscopic Anatomy, is a study of the microscopic 

 structure of the various parts of the animal body. The histologist 

 studies the relationship and arrangement of the cells as they cooper- 

 ate to comprise the substance of the organism. 



C. Cytology is the study of the minute structure of the cells which, 

 we will learn, are the units of structure of all living matter. Cytol- 

 ogy, as usually studied, includes not only the morphology of the cell 

 but a great deal of the physiology in addition. This field of study 

 has yielded many fundamental concepts of the factors involved in 

 the living process. 



2. Taxonomy is the subdivision which deals with the classifica- 

 tion or orderly arrangement of organisms according to their natu- 

 ral relationships. This field is often spoken of as systematic zool- 

 ogy. The number of described species of animals as given by dif- 

 ferent authorities ranges from 840,000 to well over a million. One 

 well-known writer says there are probably no less than 2,000,000 

 species of living animals. Besides these, there are large numbers of 

 extinct forms. It can readily be seen that a system for putting 

 these large numbers of different kinds of animals into a known 

 order is one of the first prerequisites for dealing with them. On a 

 much smaller scale, the department store is systematized for some 

 of the same reasons. One can see that it would be next to impos- 

 sible to do business if a company were to provide a large floor 

 space, go out and buy the thousands of different kinds of articles 

 that are handled by a department store, and just throw all of them 

 on its floors at random. Few customers would return a second time 

 if they had to wait hours while the clerk hunted among ladies' 

 shoes, children's toys, and men's underwear for the toothbrush the 

 customer desired. Instead of this, the store is divided into general 

 departments, and the goods are completely classified within these 

 departments. To get the toothbrush, the customer can be directed 

 to the proper department and counter, where kind, color, size, and 



