COSMIC PHILOSOPHY 



will apply to the case of the ear. And the force 

 of these considerations is still further increased 

 when we learn from Professor Gegenbaur that 

 the resemblances between the eyes of vertebrates 

 and the eyes of cuttle-fishes are only superficial 

 analogies, and not fundamental homologies, as 

 Mr. Mivart's very exaggerated statement might 

 lead one to suppose. 



In all these cases, here too briefly summed 

 up, natural selection must of course be regarded 

 as steadily cooperating with direct adaptation. 

 No matter whether individual variations are 

 directly called forth by environing agencies, or 

 are due to internal causes, in our ignorance of 

 which we call them fortuitous, they must equally 

 be the objects of natural selection wherever they 

 influence, in the slightest degree, the individ- 

 ual's chances of survival. Thus the theory of 

 natural selection is not superseded, but supple- 

 mented, by the class of considerations here sug- 

 gested by Mr. Mivart's objections. Ordinarily, 

 if not always, the two processes must go on in 

 concert ; and while the frequent occurrence of 

 directly adaptive changes must greatly accelerate 

 the operation of natural selection, on the other 

 hand natural selection, by weeding out all cases 

 of retrograde variation, must complete the work 

 of direct adaptation. 



There are, however, some conspicuous in- 

 stances in which natural selection seems to play 

 88 



