PREFACE. 



For several years it has been my habit, when 

 called upon to address horticultural societies, to choose 

 some topic intimately associated with the evolution of 

 domestic plants. My motives have been several. I 

 have chiefly desired to attempt to answer many of the 

 common questions which puzzle horticulturists by ap- 

 pealing to the evidences of evolution, for I am con- 

 vinced that manj^ of these questions can be answered 

 in no other 'way. I have also desired to spread a 

 knowledge of the evolution speculations and of the 

 methods of research which they suggest, amongst those 

 who deal with plants and animals, and who lead a 

 rural life. Again, I have wished to make a record 

 of a great class of most common and significant facts 

 vitally related to the study of organic evolution, but 

 which are almost wholly overlooked by students and 

 philosophers. In making these essays, I have con- 

 stantly had in mind the collation and publication of 

 them, and I have, therefore, endeavored to discuss the 

 leading problems associated with the variation and 

 evolution of cultivated plants, in order that the final 

 collection should be somewhat consecutive. 



The results of this intermittent labor I now give 

 (1) 



