PREFACE. 



As the objects intended to be subserved by this work are explained 

 in the introductory chapter, there is little need for a formal preface. 

 It may, however, be well to state that the chief aim of the work is to 

 present, in a popular and readily understood form, the chief evidences 

 of the evolution of living beings. In this view, whilst I have been 

 content to assume the reality of that process, I have also endeavoured 

 to marshal the more prominent facts of zoology and botany, which 

 serve to prove that evolution, broadly considered, is not merely a 

 name for an unknown tendency in nature, but is an actual factor 

 in the work of moulding the life with which the universe teems. A 

 considerable experience as a biological teacher has long since con- 

 vinced me that the hesitancy with which evolution is accepted, and 

 the doubt with which even cultured persons are occasionally apt to 

 view this conception of nature, arise chiefly from lack of knowledge 

 concerning the overwhelming evidences of its existence which natural 

 history presents. Doubtless a training in botany and zoology is 

 required before the case for evolution can be fully mastered, but 

 there need be no difficulty in the way of any intelligent person 

 forming a just estimate of evolution upon even an elementary 

 acquaintance with the facts of biology. I have accordingly sought 

 to bring such facts prominently before the notice of my readers, and 

 I would fain hope that even the complex topic of " development," 

 itself a strong pillar of the theory of evolution, is susceptible of easy 

 appreciation when the facts and inferences to be drawn therefrom are 



