CHAP. IX.] NATUEAL SELECTION. 291 



that there is much positive evidence of the direct action both 

 of external influences sufficient to dominate and overpower 

 in certain instances the ordinary processes of &quot; natural selec 

 tion,&quot; and also of still more influential internal powers ; more 

 over, that these latter powers are so efficient as to present 

 themselves as probably the main determining agent in specific 

 evolution, although it was admitted that a certain subordinate 

 action of natural selection plainly obtained. 



The various arguments advanced space does not now allow 

 the reproduction of, but referring to the Genesis of Species, 

 it may here be pointed out that therein the object aimed at 

 was to show : 



1 . That no mere survival of the fittest accidental variations 

 can account for the incipient stages of structures Points con- 

 useful enough when once developed. Such, e. g., the author. 

 as the whalebone of the whale s mouth, the larynx of the 

 kangaroo, pedicellariee and bird s-head processes, and many 

 other structures. 



2. That the sexual colours of apes, the beauty of shell 

 fish, and the complex mechanisms by which fertilisation is 

 effected in many orchids, are quite beyond the power of 

 natural selection to develop. 



3. That modes of formation, such as in the human eye 

 and ear, in that they spring from simultaneous and con 

 current modifications of distinct parts, have a remarkable 

 significance. 



4. That the independent origin of similar structures in 

 very different animal forms should be noted, and evidence was 

 adduced to show that similar modifications are sometimes 

 directly induced by obscure external conditions, as in the 

 sudden acclimatisation of English greyhounds in Mexico, 

 and in the loss of the tail in certain butterflies of certain re 

 gions, and in the direct modification of young English oysters 

 when transported to the shore of the Mediterranean. More 

 over, it was shown that certain groups of organic forms exhibit 

 a common tendency to remarkable developments of particular 

 kinds, as is the case with birds of paradise. 



u 2 



