• Introduction 21 



emphasis as it is impossible to understand any one aspect of biology 

 without taking account of others. 



The study of the animals themselves or their parts may be ap- 

 proached in two ways: their general structure or anatomy, or their 

 functioning or physiology. There are many divisions of zoology which 

 can be approached from either or both of these viewpoints. Some of 

 these are as follows : 



Histology : The study of tissues. 



Cytology : The study of cells. 



Embryology: The study of individual development. 



Pathology: The study of diseased tissues. 



Ecology: The study of how plants and animals live together. 



Genetics : The study of how living things inherit. 



Taxonomy : The classification or naming of animals. 



Endocrinology: The study of the endocrine glands. 



Morphology: The study of body form. 



Groups of animals may be studied in all the above details and also 

 from a strictly anatomical or physiological viewpoint. Some of these 

 subjects are as follows: 



Entomology : The study of insects. 



Mammalogy : The study of mammals. 



Herpetology : The study of reptiles. 



Ornithology: The study of birds. 



Parasitology: The study of parasites. 



Protozoology : The study of protozoans. 



Arachnology : The study of arachnids. 



Ichthyology : The study of fish. 



Scientists working in the above-named fields have established, and 

 at present are still establishing, the basic principles which have led 

 to our greater understanding of the living world. Applications of these 

 principles have resulted in the development of the applied fields of 

 biology which have contributed so much to better health, food, and 

 shelter. Some of these fields are : agriculture with its many branches 

 such as animal and plant breeding, dairy husbandry, veterinary medi- 

 cine, etc ; pharmacy dealing with the efifects of drugs on the animal body ; 

 medicine ; and conservation dealing with the wise use of natural resources. 



The Importance of Zoology.— Zoology as a science is useful both 

 from aesthetic and utilitarian viewpoints. For the study of medicine 

 and its allied fields, agriculture, conservation, and many other fields, 



