PREFACE. 



It is my hope that this book will be of some 

 service as an introduction to the study of Evolu- 

 tion. Not a few people who have a taste for 

 Natural History seem unable to grasp the ap- 

 plication of the Darwinian doctrine to the every- 

 day world about them, and I feel sure that 

 many of these will thank me for showing how 

 interesting some of the most trivial and common- 

 place facts about animals become when viewed in 

 this lisfht. 



Several of the chapters have been founded 

 upon articles which were written originally for 

 young students in the United States and were 

 published in the ' North American Review.' 

 The greater part of that on Dogs appeared in 

 the 'Contemporary Review,' under the title of 



