DARWINISM ATTACKED. 



races are unstable ; they revert 

 easily to the ancestral type if 

 allowed to run wild ; this is so 

 probably because of their recent 

 origin. 



(7) The artificially-produced 

 races of the same species are 

 in most cases fertile among 

 themselves. 



ties) are stable; they do not 

 revert if the outer conditions 

 (environment) remain constant; 

 this is so probably because they 

 are more firmly established by 

 reason of greater age. 

 (7) Natural varieties do not 

 cross in nature, either with 

 each other or with the ancestral 

 type. 



The most important contrast between the two kinds of 

 selection lies, in my eyes at least, in the results obtained in 

 the character of the new forms. As Morgan 2 well says, 

 "we should not lose sight of the fact that even after the most 

 rigorous selective process has been brought to bear on 

 organisms, namely, by isolation under domestication, w r e do 

 not apparently find ourselves gradually approaching nearer 

 and nearer to the formation of new species, but we find, on 

 the contrary, that we have produced something quite differ- 

 ent. In the lisfht of this truth, the relation between the two 



o 7 



selective theories may appear quite different from the inter- 

 pretation that Darwin gives of it. We may well doubt 

 whether nature does select so much better than does man, 

 and whether she has ever made new species in this way." 



De Vries expresses very positively his belief that no artifi- 

 cial races are fixed and constant forms, in the sense that 

 natural varieties are. And this difference he believes to rest 

 on the radicallv different method " of origin of the two 



J 



kinds of forms ; the domestic ones through carefully main- 

 tained selection ; the natural ones through definitive imme- 

 diately fixed and enduring mutations. 



If one stops to recall his own familiar knowledge of the 

 cultivated plants ' and will roughly classify the cultivated 

 fruits and vegetables and ornamental plants with which he is 

 acquainted into two categories depending upon the mode of 

 reproduction, that is whether by division or by seeds, one 

 will be struck by the great preponderance of the first of the 



