PKEFACE TO FIRST EDITION 



The important problems of life are common to all animals (includ- 

 ing man) as well as to plants. It should be the purpose of a textbook 

 in general zoology to present the animal kingdom in a logical and 

 natural way and at the same time carry the interpretation of the facts 

 in terms of the principles involved. It is exceedingly difficult to 

 strike the ideal balance between the necessity of presenting sufficient, 

 factual, "type" material in order that the student will have the 

 requisite knowledge of classification, structure, function, development, 

 and organography to appreciate the discussion of principles, and the 

 opposite temptation to go into endless discussions of theories and 

 rules, the comprehension of which is unquestionably beyond the 

 capacity of the student who has not become grounded in fundamentals 

 of animal make-up. Of course it is usually hoped that the laboratory 

 division of the course wiU supply this needed foundation. It seems 

 reasonable that the ultimate aim of the teacher of introductory zoology 

 should be to bring the student to a fundamental and well-grounded 

 understanding of the principles involved in all of the living processes. 

 It is extremely difficult to skim this information from the top of the 

 entire body of zoological knoAvledge, as one can skim cream from a 

 crock of milk, and hand-feed it to the waiting student mind. Ap- 

 parently there must be a certain amount of personal acquisition of the 

 principles of the subject through attaining a clear-cut knowledge of 

 tlie complete biology of a series of representative animals. Each of 

 these representatives, since it is a living organism, demonstrates cer- 

 tain of these principles. In order to bring this out there must be a 

 rather close coordination between the studies of the laboratory and 

 the presentation of principles by the textbook. 



Based on a recognition of the above-mentioned situation and also 

 on the realization that the majority of students taking elementary 

 zoology plan to go no further in the field, the author has attempted 

 to strike a workable combination of the two schools of teaching and 

 still cover the fundamental knowledge of the subject. There has been 

 a definite effort to lead the student to think of biology as related to 

 humankind and to himself. It is hoped that the book will overlap 

 the laboratory studies just far enough to lift the student out of the 

 laboratory into his o^vn correct interpretation of the facts discovered 



