Criticisms of Theory of Natural Selection. 357 



structures are useless, it necessarily follows that natural 

 selection can have had no part whatever in their 

 inception. Now, this is a conclusion which does not 

 " necessarily " follow. Even if it be granted that there 

 are structures which in their first beginnings are not 

 of any use at all for any purpose, it is still possible 

 that they may owe their origin to natural selection 

 not indeed directly, but indirectly. This possibility 

 arises from the occurrence in nature of a principle 

 which has been called the Correlation of Growth. 



Mr. Darwin, who has paid more attention to this 

 matter than any other writer, has shown, in consider- 

 able detail, that all the parts of any given organism 

 are so intimately bound together, or so mutually 

 dependent upon each other, that when one part is 

 caused to change by means of natural selection, some 

 other parts are very likely to undergo modification as 

 a consequence. For example, there are several kinds 

 of domesticated pigeons and fowls, which grow peculiar 

 wing-like feathers on the feet. These are quite unlike 

 all the other feathers in the animal, except those of 

 the wing, to which they bear a very remarkable re- 

 semblance. Mr. Darwin records the case of a bantam 

 where these wing-like feathers were nine inches in 

 length, and I have myself seen a pigeon where they 

 reproduced upon the feet a close imitation of the 

 different kinds of feathers which occupy homologous 

 positions in the wing primaries, secondaries, and 

 tertiaries all being distinctly repeated in their proper 

 anatomical relations. Furthermore, in this case, 

 as in most cases where such wing-feathers occur 

 upon the feet, the third and fourth toes were partly 

 united by skin ; and, as is welj known, in the wing 



