vin DARWINISM AND HOLISM 197 



appear, not as the result of a slow age-long summation of 

 small variations, but at one bound, with a great leap of one 

 generation to the next. An individual of species X produces 

 offspring which constitute a stable variety or a new species 

 Y. De Vries saw this happening in the case of cultivated 

 (Enothera lamarckiana growing wild in a potato-field at 

 Hilversum in Holland. Other instances have been observed 

 by other investigators. It is objected that De Vries's 

 CEnothera was perhaps a cultivated artificial hybrid, with 

 mixed qualities, like the ab^s of the Mendelians, and that 

 all he observed was the emergence of pure qualities from 

 this mixture; in other words, not the emergence of new 

 characters but the setting free and unmasking of concealed 

 or latent characters already existing. Other criticisms also 

 have been levelled at the Mutation theory which it is not 

 necessary for our purpose to consider here. In spite of 

 these criticisms it is practically certain that mutations do 

 take place in the course of Evolution. But while they almost 

 certainly happen on special occasions, they are not common 

 and do not constitute the ordinary method of organic Evo- 

 lution. On rare occasions there is a saltus, a creative leap 

 forward from one generation to another. A species having 

 long balanced itself precariously on the edge of a great 

 change suddenly makes the jump, secures a foothold on the 

 edge of the other side, and marks the beginning of a new 

 variety or species. But it can at best only be an exceptional 

 if not rare effort on the part of Nature. These sudden long 

 jumps can only be very occasional, and not the normal 

 course or procedure in the origin of species. Otherwise we 

 would certainly see more of them, and they would not be 

 the subject of doubt or dispute. The rarity of their observa- 

 tion points to the rarity of their occurrence. And they 

 must be largely confined to cultivated artificial species or 

 varieties which are more unstable and violently variable 

 than natural species or varieties. Mutation in wild nature 

 is an occasional and exceptional occurrence, and is not the 

 ordinary procedure of Evolution. 



Having thus ruled out both Mendelism and De Vries^s 



