DISCONTINUOUS VARIATION. 59 



not producing ancon offspring." Again, Darwin says: * 

 " It is certain that the ancon and the mauchamp breeds 

 of sheep, and almost certain that the niata cattle, turn- 

 spit and pug-dogs, jumper and frizzled fowls, short- 

 faced tumbler pigeons, hook-billed ducks, etc., suddenly 

 appeared in nearly the same state as we now see them. 

 So it has been with many cultivated plants." And 

 then he adds, " The frequency of these cases is likely to 

 lead to the false belief that natural species have often 

 originated in the same abrupt manner. But we have 

 no evidence of the appearance, or at least of the con- 

 tinued procreation, under nature, of abrupt modifica- 

 tions of structure." 



We see therefore that, though Darwin brought for- 

 ward much more powerful and convincing instances of 

 discontinuous variation than those cited by Bateson, he 

 held them to be quite inadequate to account in any way 

 for the discontinuity observed in species. 



Under the title of " Die Mutationstheorie" De Yries 

 has recently promulgated views concerning the origin 

 of species which are somewhat similar to those held by 

 Bateson. The evidence he adduces in support of them is 

 chiefly derived from observations of his own on flower- 

 ing plants, and even if his theoretical views be entirely 

 rejected, there can be no doubt as to the intrinsic 

 interest and importance of the observations themselves. 

 According to the theory of mutation, the qualities of 

 organisms are built up of individual units sharply 

 defined from each other. When, in the course of 

 evolution, one species arises from another, it follows 

 that the change takes place by a distinct step or jump, 



*IMd., vol. ii. p. 409. 



