Preface 



HE excellent reception and wide use ac- 

 corded the sixth edition of College Zoology 

 were very encouraging. The marked im- 

 provements in the seventh edition should 

 increase its usefulness as a textbook for be- 

 ginning students in college zoology. The 

 entire book has been reillustrated and re- 

 vised; some parts have been rewritten, others 

 added, and still others reorganized to make 

 it a comprehensive, stimulating, and up-to- 

 date work of zoological science. 



A serious effort has been made to achieve 

 a good balance between structure, function, 

 and principles. The early chapters deal 

 broadly with such subjects as classification, 

 protoplasm, cellular structure and function, 

 and the fundamental aspects of metabolism. 

 Thus, these chapters provide an introduc- 

 tion to principles that apply throughout the 

 Animal Kingdom. However, the basic plan 

 of the book has not been altered materially, 

 for it is believed that most teachers of gen- 

 eral zoology prefer the approach in which 

 animals are considered from the simple to 

 the complex, including man. There are 

 many advantages to this plan of instruc- 

 tion: (1) it aids in teaching the scientific 

 method, which involves the deduction of 

 general principles from many facts; (2) stu- 

 dents find it psychologically more satisf}'- 

 ing to proceed from the simple to the com- 

 plex, and they better retain the idea of the 

 division of labor in living things when it is 

 presented to them in this order; (3) a back- 

 ground in the study of the invertebrates 

 helps one to understand the vertebrates; 

 (4) although students may have a superfi- 

 cial acquaintance with the frog, they ac- 

 tually know little about its biology, so there 

 is serious doubt concerning the validity of 

 the argument that the frog should be stud- 

 ied first because of the student's familiarity 

 with it; ( 5 ) the great complexity of the frog 

 makes its study difficult; therefore, for psy- 

 chological reasons as well as for logical ones, 

 it should not be studied first; and (6) the 

 simple-to-complex approach best introduces 

 the student to the principle of organic 

 evolution. 



