viii Preface. 



most superficial acquaintance with the frequent 

 sports and new varieties of cultivated flowers, 

 etc., is enough to show that vegetables exhibit 

 an amount of variability far greater than any- 

 thing we have any reason to believe existing 

 among animals ; yet I cannot but think that, 

 mutatis mutandis, the general principles which 

 in the ensuing pages I attempt to trace out, will 

 be found applicable to the whole of organised 

 nature. 



What I am endeavouring to establish is not 

 the assertion or negation of any particular 

 views as to the origin of organic races, but on 

 the contrary the conviction that the whole 

 matter is beyond our present ken. But if I 

 were asked in what way the subject could 

 be brought within the area of possible science, 

 I should say that two things must be done. 



The first, and by far the easiest, of these 

 tasks is to find out by careful experiment 

 v/hat changes really can be produced in a 



