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involved, it is possible to suggest various ways in which it might 

 have been brought about. 



The line of departure of mutants from the parent type is not 

 in any one direction, and the manner of variation appears to be 

 wholly a matter of what we are pleased to call chance. As has 

 been said, de Vries obtained more than a dozen different forms. 

 Some of the mutants, we may say, are probably destined to fail- 

 ure, others perhaps are better placed, at least in new environment, 

 than the parental type and might conceivably stamp it out in time. 

 What the criteria of success or non-success may be is a matter 

 upon which no one would care to give an opinion, but I have in 

 mind the fact that one of the mutants of Lamarck's evening prim- 

 rose has a tendency to germinate somewhat more quickly than 

 the parent form, and the seedling grows a little more rapidly ; it 

 is conceivable that some slight advantage of this sort might be 

 the crucial point. However that may be, it is here that we can 

 apply the Darwinian concept of the struggle for existence, a 

 struggle however not between single individuals, as the idea of 

 continuous variation would imply, but the struggle between great 

 numbers of individuals, whole groups of elementary species. 

 The great contrast between Darwin and de Vries is the contrast 

 between the slow and continuous accretion of variations implied 

 by the former and the sudden jumping or saltatory variation in- 

 sisted on by the latter. By such means as de Vries maintains 

 the process of evolution might take place with far greater rapid- 

 ity than by Darwin's method, for, generous as the geologists are 

 in their allowance of time for the development of organic life on 

 the world, it has always been difficult of conception how even 

 the countless ages granted could compass the enormous develop- 

 ment of the highest organic types from simple forms. To main- 

 tain that de Vries's theory is entirely complete, and must be the 

 only means of the origin of new forms, is unnecessary. None 

 but the extremists would go to such a length ; it is not at all nec- 

 essary to assume that the means to a similiar end must necessarily 

 be similar. What may be maintained, and properly so, is that 

 mutation constitutes one way, at least, by which new forms of 

 organisms may arise on the world's surface. New forms, in the 



