72 The Different Modes of Origin of new Species, 



B\. By characters already existing becoming la- 

 tent: Retrogressive specific differentiation, 

 cases of atavism. 



82- By the activation of latent characters : De- 

 gressive specific differentiation. 



a. From taxinomous (latent) anomalies. 



b. As genuine atavism. 

 ^3. From hybrids. 



'f* 'K 'T* 



This list does not of course claim to be complete. 

 There is no doubt a whole series of further types which 

 can be more or less easily ranged under or parallel to 

 these subdivisions. On the other hand it is at once clear 

 that the distinction between A and B is, in the present 

 state of our knowledge, the important thing, and more- 

 over that it will suffice as a basis for experimental in- 

 quiry. But before I proceed to illustrate this antithesis 

 I will offer some remarks on the last section (Bs). 



New species can arise from hybrids but specific char- 

 acters cannot arise by means of hybridization; or, we may 

 say that with regard to the production of mutations, hy- 

 brids behave just like ordinary species, except that ac- 

 cording to the prevalent view they are slightly more 

 prone to it. The existence of a vast number of species, 

 however, is due to the various combinations of characters 

 which also exist in closely allied or in remote species. 

 And it is evident that, by crossing, characters can be com- 

 bined which have not appeared in the same genealogical 

 line but in distinct though allied species. Thus for ex- 

 ample by crossing Oenothera rubrinervis with 0. nanella 

 I obtained an 0. rubrinervis-nanella which has remained 

 constant for many generations without segregation and 



