PREFACE. 



This book is intended to help those who would study 

 animal life. From different points of view I have made 

 a series of sketches. I hope that when these are united 

 in the mind of the reader, the picture will have some 

 truth and beauty. 



My chief desire has been to give the student some 

 impulse to joyousness of observation and freedom of 

 judgment, rather than to satisfy that thirst for knowledge 

 which leads many to intellectual insobriety. In pursu- 

 ance of one of the aims of this series, I have also tried 

 to show how our knowledge of animal life has grown, 

 and how much room there is for it still to grow. 



A glance at the table of contents will show the plan 

 of the book ; first, the everyday life of animals, next, their 

 internal activities, thirdly, their forms and structure, and 

 finally, the theory of animal life. This is a commonly 

 accepted mode of treatment, and it is one by which it is 

 possible in different parts of the book to appeal to students 

 of different tastes. For, in lecturing to those who attend 

 University Extension Courses, I find that seniors are 

 most interested in the general problems of evolution, 

 heredity, and environment ; that others care more about 

 the actual forms of life and their structure ; that many 

 desire to have a clear understanding of the functions of 

 the animal body ; while most wish to study the ways of 

 living animals, their struggles and loves, their homes and 



