PREFATORY NOTE 



This book is a simple introduction to the study of the 

 structure, physiology, behavior and classification of animals 

 and to the study of the make-up and physiology of the 

 human body. It makes use of some of what have been 

 proved by experience to be the most useful parts — specially 

 revised for this book — of the author's "Elementary Zoology" 

 and "First Lessons in Zoology," to which have been added 

 new chapters on human structure and physiology and on 

 certain special relations between animals and man. The 

 whole book has been written and arranged from the point 

 of view of a biologist intent on making our knowledge of 

 the make-up and life of the lower animals help in under- 

 standing human structure and physiology and in contributing 

 to human welfare. I believe that this point of view need not 

 militate in the least against the disciplinary or informational 

 value of a text-book of zoology. I believe, indeed, that it 

 will enhance these values. 



Chapters XXI to XXVIII, on human structure and 

 physiology, were written by Assistant Professor Isabel 

 McCracken of this University, and to that extent Miss 

 McCracken is joint author of the book. 



I wish to acknowledge my indebtedness to those numerous 

 zoologists who have accorded me permission to use illustra- 

 tions original with them. The sources of these repeated 

 illustrations are indicated in the captions of the pictures. 

 The drawings for the figures original with me have mostly 

 been made by Miss Mary Wellman and Mr. Sekko Shimada 

 to both of whom I am under obligation for their intelligent 

 and skilful help. 



V. L. K. 

 Stanford University, January, 1911. 



