274 DARWINISM TO-DAY. 



of the inheritance of acquired characters in some degree or 

 under certain conditions and this partial acceptance has 

 always seemed to me no more justified than the flat accept- 

 ance of the principle in its entirety; it has seemed a weak 

 sort of attempt at compromise with no real basis in reason 

 and effecting no advantage in clearing up the problem 

 there can be no acceptance of the all-sufficiency of Lamarck- 

 ism as an explanation of adaptation, species-forming, and 

 descent, any more than there can be such an acceptance of 

 the all-sufficiency of natural selection. Adaptation and spe- 

 cies-forming are not, to my mind, one and the same problem : 

 adaptation can and does lead to species-forming, but species 

 are formed that are not the results of adaptive modifica- 

 tion ; whose specific characteristics are indifferent ; that are, 

 in a word, non-adaptive species. De Vries's new species of 

 evening primroses have a cause not associated with adapta- 

 tion. Now Lamarckism certainly cannot explain non- 

 adaptive species any better than selection can. Both selec- 

 tion and the inheritance of the effects of use, disuse, and 

 external stimuli are primarily explanations of adaptations 

 and of adaptive species-forming. Lamarckism is, perhaps,, 

 through its inclusion of the perpetuation of the direct influ- 

 ence of external stimuli, in better condition to explain non- 

 adaptive species, but both of these genius-offered explana- 

 tions of organic evolution need the aid of another or other 

 factors : the unknown factors of evolution, to speak with 

 Osborn. 



Orthogenesis. One of the principal criticisms of the 

 natural selection theory is that of the impossibility of ex- 

 plaining- the beginnings of advantageous modi- 

 Apparent evi- J 



dence for ortho- fication and the beginnings of new organs, by 

 genetic evolution, the se i ect i on o f fluctuating individual variation, 

 and of explaining the apparent cases of the existence of 

 determinate variation and the admitted cases of forthright 

 development along fixed lines not apparently advantageous,, 



