DARWIN', AND THE ORIGIN OF SPECIES 1 97 



win's explanation of the struggle for existence can believe any 

 useful structure will, in nature, be without selective value. All 

 who grasp the meaning of the struggle for existence, which nature 

 exhibits to all who have eyes to see, must agree with Darwin 

 that, " owing to this struggle, variations, however slight, and from 

 whatever cause proceeding, if they be, in any degree, profitable to 

 the individuals of a species, in their infinitely complex relations 

 to other organic beings and to their physical conditions of life, will 

 tend to the preservation of such individuals." ^ 



If the opinion that natural selection cannot account for the 

 incipient stages of useful structures did not exhibit such vitality, 

 there would be no reason to dwell upon it ; but as Romanes's 

 book shows that thoughtful men still find it a real difficulty, I 

 shall now examine two adaptations which have been used to illus- 

 trate the difficulty. 



In a chapter which he added to the later editions of the 

 " Origin," Darwin says that *' after reading with care Mr. Mivart's 

 book, and comparing each section with what I have said on the 

 same head, I never before felt so strongly convinced of the gen- 

 eral truth of the conclusions here arrived at"; although few illus- 

 trations of the extent and accuracy and minuteness of Darwin's 

 acquaintance with nature are more impressive than his demon- 

 stration of the existence of useful adjustments similar to the 

 incipient stages in the very adaptations which Mivart uses to 

 prove his assertion that " natural selection cannot account for the 

 incipient stages of useful structures." 



"The Greenland whale," says Darwin, "is one of the most won- 

 derful animals in the world, and the baleen, or whalebone, one of 

 its greatest peculiarities. The baleen consists of a row, on each 

 side of the upper jaw, of about three hundred plates or laminae, 

 which stand close together transversely to the long axis of the 

 mouth. Within the main row there are some subsidiary rows. 

 The extremities and inner margins of the plates are frayed with 

 stiff bristles, which clothe the whole gigantic palate, and serve 

 to strain or sift the water, and thus secure the minute prey on 

 which these great animals subsist. The middle and longest 

 lamina in the Greenland whale is ten, twelve, or even fifteen 



^ " Origin," p. 49. 



