1J6 THE LESSON OF EVOLUTION 



But natural selection cannot act unless favourable 

 variations arise, and this is not always the case. For 

 example, fish are very scarce at Campbell Island, 

 and, according to Dr. H. Filhol, who lived there for 

 four months, the Campbell Island cormorant feeds on 

 the mollusks that live on the brown seaweed or kelp. 

 So great a change in habits would seem to demand 

 some modification of the bill, which cannot be the 

 best possible instrument for detaching shell-fish from 

 seaweed, seeing that it was intended for catching 

 fish. Probably also some modification of the feet 

 would be useful, for the birds have no longer to 

 swim fast, but to crawl about among the seaweed. 

 However, no such modifications have occurred, 

 although the birds have probably been living on the 

 island for a very long time. 



This is by no means an isolated fact. Penguins 

 obtain their food entirely by diving, and they have 

 been in existence since the Oligocene period ; yet 

 they have not developed any modification to assist 

 them in remaining under water ; while the webbed 

 feet of the Upland-goose of Patagonia prove that 

 natural selection cannot always correct imperfect 

 adaptations. These, and similar cases, go to shew 

 that natural selection is not such an all-searching 

 power as the Neo-Darwinians suppose, and that it 

 cannot bring about close adaptation in every case. 



A point generally overlooked is that by means of 

 natural selection a genus may sometimes be formed 

 after the species contained in it. In times of 

 changing conditions individuals of several species 

 may be preserved owing to their all possessing a 



