viii PREFACE TO THE FIRST EDITION 



an integral part of the course. Such a systematic survey can 

 best be undertaken toward the end of the year when the stu- 

 dent through his laboratory work has obtained sufficient familiar- 

 ity with animal forms and taxonomy to make it worth while. 

 Incidentally there is perhaps no better way to review or sum- 

 marize the course and to bring out vividly the applications of 

 biological principles. The author realizes that principles are 

 based upon facts and that logically facts should come first; the 

 plan of presentation followed here is a compromise which is suc- 

 cessful with beginning students and which at the same times does 

 not violate standards of scientific method. 



In the laboratory the endeavor is made to have the student 

 obtain a substantial knowledge of a relatively few animal forms as 

 whole organisms rather than a smattering acquaintance with 

 parts of many. Selection of animal forms for laboratory study is 

 a matter of judgment guided by experience. The author has 

 found it best to begin with a relatively large animal, like the frog, 

 then turning to Protozoa and working up the scale. This general 

 program is broken into from time to time with special demonstra- 

 tions, collecting trips and visits to the zoological garden. For 

 the laboratory work mimeographed directions are used similar 

 to those used in the work in other places. 



Naturally it is not always possible to correlate lecture and 

 laboratory work but the class-room instructor constantly bears 

 in mind what the student is doing in the laboratory and, so far 

 as possible, makes full use of the student's laboratory experience 

 in dealing with the subject under discussion. Free use of special 

 demonstrations helps to obviate this difficulty. 



In the compilation of the material for this book the author has 

 made use of many sources which are acknowledged in the text and 

 in the lists of references at the ends of chapters. The majority 

 of the illustrations are new drawings based upon the author's 

 material or figures of others; the remainder have been taken 

 directly from other works with the permission of the publishers 

 whose courteous cooperation is duly appreciated. The author 

 is also indebted to his wife for valuable assistance of a miscel- 

 laneous sort at each stage of the book's progress; and to Dr. 

 C. V. Piper for helpful editorial suggestions. 



Cincinnati, O. H. L. Wieman. 



June, 1925. 



