OTHER THEORIES OF SPECIES-FORMING. 333 



mary variations," which are large and sudden as contrasted 

 with "secondary variations," which are the usual small, 

 , fluctuating or so-called Darwinian variations, 



ory of "primary Emery bases his belief on the few cases like 

 variations," ^ ^ncon sheep and the inherited six-fingered- 

 ness of men, and also on an argument drawn from the dif- 

 ficulty of explaining by the natural selection theory various 

 -existing conditions such as sexual polymorphism, and numer- 

 ous cases of extremely complex structural and physiological 

 specialisation. But there is little that is convincing in 

 Emery's presentation. 



A later exponent of heterogenesis of a different kind, and 



a more sharply-spoken antagonist of the selection theory, 



much more nearly anticipates de Vries's muta- 



Korscliinsky's 



theory of hetero- tion theory. Indeed this biologist, the Russian 

 botanist Korschinsky, in his championship of 

 heterogenesis goes much beyond de Vries in his denial of the 

 influence of selection in species-forming and descent. De 

 Vries, as we shall see, admits natural selection to be a factor, 

 and perhaps a large one in the determination of descent, of 

 organic evolution, but holds it to be wholly a restraining and 

 cutting-back factor, not at all a formative one. Korschinsky 

 says plainly that the struggle for existence and selection 

 have either no influence in species-forming and descent, or, 

 if any, a hindering and antagonising influence, a retarding 

 and nullifying influence. Korschinsky has published his 

 theory in three papers, one a large work in Russian which I 

 have not seen, the others shorter papers ll in German which 

 are of the nature of vorlailfige Mitteilungen. In these 

 papers he formulates clearly and positively a theory of 

 heterogenesis or species-forming by "mutations" and attacks 

 sharply and positively the natural selection theory. A con- 

 cise statement of his theory and at the same time of his 

 position with regard to the selection theory is given by 

 him in a table of two columns in which the contrast between 



