INTRODUCTION 33 



whose extermination is easily possible, they will advise against it 

 until all phases of the animal's existence are thoroughly investigated. 

 To wipe out this form might remove the cheek on others that are still 

 more obnoxious. Because of the danger of interfering with the nor- 

 mal balance or equilibrium in nature, our government and many 

 others have placed a restriction on importation of plants or animals. 

 One must have permission to bring either into this country. 



Zoology as Related to Man 



The values of the study of zoology may be placed in two classes: 

 cultural and practical. There is hardly a field of endeavor in the 

 realm of human activities which is not greatly influenced by zoology 

 and biology generally. The study of philosophy, the formulation 

 of our conception of religion, the comprehension of social welfare 

 problems, and many other similar intellectual and social accomplish- 

 ments are greatly facilitated by a knowledge and recognition of 

 biological principles. From the purely practical or economic side, 

 of course, agriculture, medicine, and their related sciences have 

 profited enormously. In fact, these fields are in themselves applied 

 biology. Most of the great discoveries as to the nature and control 

 of disease, the manner of inheritance of human characteristics, and 

 the knowledge of fundamental physiological processes occurring in 

 our own bodies have been attained by studies on other animals. 

 What is found to be true in a dog, frog, rabbit, rat, monkey, or 

 guinea pig, usually has its application to man. The lives of these 

 laboratory animals have made untold and inestimable contribution 

 to the welfare and comfort of man. The loss of their lives is con- 

 stantly saving millions of human lives. One of the most obvious 

 uses of other animals is as a source of food supply. All of the phyla 

 and classes of larger animals furnish at least a few species that find 

 places on our menu cards, particularly mammals, birds, turtles, 

 frogs, fish, crabs, lobsters, clams, oysters, and even snails. 



Many animals are important because of their destructive tend- 

 encies in regard to articles valued by man, or to the health and life 

 of man. Most of the predaceous animals today are not a menace 

 to man directly, but they do destroy many domesticated as well as 

 useful wild animals. It is likely that the parasites which live on 

 and in the bodies of men, and on domesticated plants and animals 

 have been much more costly than the depredations of the more 

 conspicuous predators. 



