CHAPTER XXVII 

 ANIMAL LIFE AND EVOLUTION 



In all this book so far, we have made but little reference to 

 that phase of the study of animals which is usually called 

 animal evolution, or animal bionomics. We have taken the 

 many species of animals, and the great variety of form and 

 manner of life of these species, as facts, not problems; and we 

 have even described many kinds of extraordinary adaptations, 

 or modifications of structure and life to fit their possessors to 

 special or unusual conditions, without suggesting that the ques- 

 tion of the origin of these adaptations presents perhaps the 

 most important and attractive problem in all the study of 

 animals. We have postponed all such references deliberately 

 in order, primarily, to accent the facts and problems of eco- 

 nomic zoology throughout the book, and, secondarily, so that we 

 might take up the evolutionary phase of animal life in a single 

 compact chapter which should present an outline of the present- 

 day status of knowledge and speculation on the subject. By 

 putting this chapter of the book last in the present part we hope 

 to leave as a final impression in the elementary zoologist's 

 mind a special stimulus to further interest in and study of 

 animal life. For it is exactly the evolutionary phase of animal 

 study, the pursuit, that is, of the solution of questions as to the 

 why and how and the origin and change in animal form and 

 function and in animal kinds, which is the chief inspiration for 

 the really philosophic study of animal life. The usefulness of 

 knowing animals and their life, the enjoyment from a trained 

 observation of their manifold forms and behavior, and the drill 

 obtained from a careful study of their anatomy and physiology, 

 are all really achieved by human endeavor of a different type 

 from that required for the solution of evolutionary problems. 

 And all of them are much more really within the possible grasp 



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