PREFACE 



THIS book has been written for the use of students taking the 

 introductory course in Zoology in Universities and Colleges. It 

 has been prepared especially for the zoological part of the work 

 in General Biology at the University of Michigan, and is ex- 

 pected to supplement the one lecture and four hours of labora- 

 tory work per week during the first half year. 



No textbook now on the market covers the field of the intro- 

 ductory course in Zoology as it is given at several of the leading 

 Universities. These courses deal with invertebrate types only, 

 being followed by a course on vertebrate types during the second 

 half year. Only a few animals belonging to the more important 

 phyla, as viewed from an evolutionary standpoint, are considered. 

 They are, however, intensively studied in an endeavor to teach 

 the fundamental principles of Zoology in a way that is not pos- 

 sible when a superficial examination of types from all the phyla 

 is made. Furthermore, morphology is not specially emphasized, 

 but is coordinated with physiology, ecology, and behavior, and 

 serves to illustrate by a comparative study the probable course of 

 evolution. The animals are not treated as inert objects for 

 dissection, but as living organisms whose activities are of funda- 

 mental importance. No arguments, I believe, are necessary to 

 justify this method of procedure, since the so-called " type 

 course," developed with the problems of organic evolution in 

 mind, and dealing with dynamic as well as static phenomena, is 

 recognized by most teachers at the present time as the best 

 method of introducing young students to Zoology. 



The author has taught a course similar to that just outlined at 



the University of Wisconsin and to three successive classes at the 







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