PREFACE. 



THE ESSAYS included in this volume have appeared from time to 

 time in various magazines. I may discover justification, if such be 

 needed, for their publication in their present form, in the fact that 

 this method of rendering permanent views and opinions which would 

 otherwise vanish away with magazine " back stock," finds favour in 

 the eyes of many readers, and has besides become a common prac- 

 tice of our day. The sole aim of the Essays now collected will be 

 fulfilled if they succeed in explaining, to those " willing to know," 

 some of the great facts and laws which underlie the every-day life both 

 of man and his lower neighbours animals and plants alike. There 

 are many less effective things, in the way of modern culture, than a 

 popular training in biology. To aid such culture in its own small 

 measure is the chief object of the present volume. 



To Messrs. Longmans & Co. I have to express my best thanks 

 for kindly permitting the reprinting of the articles on "Human 

 Resemblances to Lower Life " and " Some Economics of Nature," 

 which originally appeared in " Longman's Magazine." 



A. W. 



EDINBURGH: February 1887. 



