PREFACE 



This text was written as a general survey of modern zoology for 

 use by college students and to serve as a reference book for biologists. 

 In the author's attempt to include in the introductory course not 

 only the basic principles so obviously essential to a general culture 

 course in animal biology, but also to satisfy the needs of students 

 entering medicine and agriculture, he has found it desirable to em- 

 phasize physiology, ecology and applied zoology. Many of the 

 most interesting portions of this text have been introduced as a 

 result of inquiries by keen students. 



After using much of the subject matter as a mimeographed text, 

 the author prepared the manuscript in its final form, and during 

 three summers has availed himself of the aid of many specialists 

 at the Marine Biological Laboratory, Woods Hole, Mass. Through 

 the interest of various authorities who gave advance information 

 about their work, certain chapters include material prior to the 

 actual publication of the research discussed. 



Some of the most important features of the book are the logical 

 arrangement of facts about the animals within a group, a statement 

 of the chief characteristics at the beginning of the discussion, and a 

 summary on the economic importance at the end of each section. 

 The newer physiology has been introduced and a bibliography 

 checked by experts in each field is given at the end of each chapter. 

 Sources readily available have been selected and resumes chosen 

 instead of the pioneer researches. Extensive discussions of Embry- 

 ology and Animal Behavior have been found undesirable since such 

 studies cannot be comprehensively treated in an introductory course 

 without excluding other fundamental subjects. 



The writer takes pleasure in thanking the following colleagues 

 at West Virginia University: Dr. A. M. Reese, Dr. L. H. Taylor, 

 Mr. A. G. Eaton, Dr. L. H. Peairs, Dr. A. J. Dadisman, Mr. Chan- 

 dler Brooks, Dr. J. A. Eiesland, Dr. P. D. Strausbaugh, Dr. A. J. 

 Hare, Dr. F. B. Trotter and Dr. C. G. Brouzas. 



Certain chapters have, furthermore, received the benefit of criti- 

 cism by the following specialists: Dr. G. N. Calkins and Dr. C. A. 

 Kofoid, Protozoa; Dr. M. M. Metcalf, Evolution; Dr. C. E. Mc- 



