THE AMERICAN NATURALIST [Vol. XLIII 



the way in which it would ease him over that difficult 

 subject, the imperfection of the geological record, and 

 would reconcile him with the physicists and cosmogonists 

 who were not disposed to allow him the lapse of past time 

 he required for the evolution of species by the accumu- 

 lation of successive minute or " insensible " individual 

 variations. But I will not discuss these points now. 

 What I wish to dwell upon at the moment is that Darwin 

 recognized and accepted the fact of mutation among ani- 

 mals and plants under domestication, although it is worth 

 while to repeat the statement that some of his cases 

 probably happened in a state of nature, since they oc- 

 curred at the very beginning of, and were the points of 

 origination for, man's selective operations. As Mr. 

 Darwin himself says: "Man can hardly select, or only 

 with much difficulty, any deviation of structure excepting 

 such as is externally visible, " s which means, as I take it, 

 that nature usually presents some quite manifest varia- 

 tion before artificial selection begins, and this must have 

 been the case at the time when man's first choices were 

 made, particularly when half-civilized and unobserving 

 men began the cultivation of our now domesticated ani- 

 mals and plants. It is necessary to remember, however, 

 in .this connection, that the mutation theory, as inter- 

 preted by De Vries, requires for its starting point only 

 a variation which marks a distinct separation of a form 

 from its parent group without connecting gradations, and 

 not necessarily any great or extraordinary change of 

 characters; for, as he says: -Species arc derived from 

 other species by means of sudden small changes which, 

 in some instances, may be scarcely perceptible to the 

 inexperienced eye." None the less it remains true that 

 man is apt to select only striking variations and hence 

 Mr. Darwin, in treating of "sports," or what we should 

 now call mutants, among cultivated plants and animals, 



or. rather, lie deals only with such asl,,, large deviations'. 



