Wallace's Selection Theory. 41 



point. This point concerns the principle of the inherit- 

 ance of variations and the artificial improvement of 

 races by selection. In many cases cultivated forms have 

 become so different from their wild ancestors by this 

 means, that they can scarcely be recognized as their 

 descendants. But the word races has evidently a double 

 signification. It means not only the races improved by 

 selection, but also the constant subspecies of unknown 

 origin which already exist. ^ Without doubt many culti- 

 vated forms diverge to a certain extent from the species 

 to which they are considered to belong by systematists. 

 But these forms are subspecies and their common origin 

 from a single species is just as good a hypothesis as that 

 of the common origin of the species of a genus. Culti- 

 vated subspecies are in well-known cases older than cul- 

 tivation itself; as Wallace himself for example shows 

 in the case of the races of the dog.^ How they have 

 arisen we do not know, not even in the case of those that 

 have probably arisen in a state of domestication. 



On this slender foundation Wallace now proceeds 

 to build further, and says, p. 12: ''It is therefore proved 

 that if any particular kind of variation is preserved and 

 bred from, the variation itself goes on increasing in 

 amount to an enormous extent; and the hearing of this 

 on the question of the origin of species is most im- 

 portant/' 



But this thesis is by no means proved ; on the con- 

 trary its truth is only assumed for the sake of the argu- 

 ment both by Darwin and Wallace, and by the mass 

 of their followers. 



Wallace evades this point in his book; he neither 



^ As for instance the races of mankind. 

 ^ Loc. cit., p. 88. 



