PROBLEM OF ORIGIN OF SPECIES 43 



Darwin and others, covers two classes of phenomena, totally distinct 

 in nature, action, and effect. Variation proper is defined as the 

 ordinary, fluctuating, or individual variation, and this is held to be 

 absolutely impotent to form new species. 



It is claimed that no amount of either natural or artificial selection 

 can by any possibility lead this variation up to the birth of a new 

 species. The utmost that could be attained would be an improved 

 race that would inevitably revert to the original state as soon as left 

 to itself. 



Mutation, on the other hand, never advances by slow and minute 

 modifications, which are continuous and cumulative, but by single, 

 sudden jumps. In the words of De Vries: "Species have not arisen 

 through gradual selection, continued for hundreds or thousands 

 of years, but by jumps (stufenweise) through sudden, though small, 

 transformations. In contrast with variations which are changes 

 advancing in a linear direction, the transformations to be called 

 mutations diverge in new directions. They take place, then, so far 

 as experience goes, without definite direction." (Vol. i, p. 150.) 



The new species arises from the old, but without any visible pre- 

 paratory steps, and without intermediate connecting stages. Like 

 the old, it is subject to variation, but as a type, it is essentially 

 immutable. 



De Vries does not deny that variation produces what may appear 

 to be transitional forms, but he maintains that these forms in reality 

 have no such meaning. They are to be regarded as phenomena of 

 " transgressive variability," which may obscure, but not obliterate 

 the specific limits. 



"For," says De Vries, "the transitions do not appear before the 

 new species, at most only simultaneously with this, and generally 

 only after this is already in existence. The transitions are therefore 

 no intermediates or preparations for the appearance of the new 

 forms. The origin takes place, not through them, but wholly inde- 

 pendently of them." (Vol. i, p. 362.) 



Granting that the position with respect to the mutants obtained 

 from the evening primrose ((Enoihera Lamarckiana) is unassailable, 

 does it follow that all new species have arisen by mutation, and 

 that continuous variation has never had, and never can have, any- 

 thing to do with the origin of species? 



Plausible as is the argument and impressive as is the array of evi- 

 dence presented, I can but feel that there are reasons which compel 

 us to suspend judgment for a while on this pivotal point of the muta- 

 tion theory. America is the original home of the evening primroses, 

 and it is here that the natural history of the group remains to be 

 worked out in the light of the experimental results obtained in 

 Holland. 



