378 Origin of Each Species Considered Separately. 



obviously one of the most unfavorable characters that 

 a species can possess ; and the theory of selection which 

 can only explain the origin of favorable characters can- 

 not account for the existence of unfavorable ones. 



According to the mutation theory a species, even if 

 it is so weak that it can hardly maintain itself, and can 

 only just reproduce itself, is capable of existing, for a 

 time, alongside the parent species. Oenothera hrevistylis, 

 which hardly sets any seed and yet has maintained itself 

 amongst the Lamarckianas at Hilversum since 1887, 

 proves the correctness of this view. At some future 

 date no doubt, if the struggle for existence becomes 

 keener, it w^ill give way to Lamarckiana or be vanquished 

 in the struggle with other plants whilst Lamarckiana may 

 survive. But if the conditions of life remain as they 

 have been up to now, there is at least the possibility that 

 O. hrevistylis may continue to exist alongside La- 

 marckiana.^ 



This difficulty can be avoided by confining the term 

 species to those forms which have emerged victorious 

 from the struggle for existence. But such a limitation 

 of the meannig of the term would of course be perfectly 

 arbitrary and only serve to further confuse a problem 

 already sufficiently difficult. 



The doctrine of mutation on the other hand makes 

 it easy to see how species may arise and yet be disquali- 

 fied for survival for any length of time. Mutability 

 produces deviations in all directions (I, § 26, p. 198) ; it 

 is absolutely uninfluenced by the greater or lesser utilit}^ 

 of the changes it produces. It simply produces varia- 

 tions, leaving it to the struggle for existence to decide 

 whether they are in the right direction or not. But the 



^ It still occurred in that locality in 1907. (Note of 1908.) 



