2 jo Darwin, and after Darwin. 



generations ceased to require their legs, their eyes, 

 and so forth, all such organs of high elaboration have 

 either disappeared or become vestigial, leaving the 

 parasite as a more or less effete representative of its 

 ancestry. 



These facts of degeneration, as we have previously 

 seen, are of very general occurrence, and it is evident 

 that their importance in the field of organic evolution 

 as a whole has been very great. Moreover, it ought to 

 be particularly observed that, as just indicated, the facts 

 may be due either to a passive cessation of selection, or 

 to an active reversal of it. Or, more correctly, these 

 facts are probably always due to the cessation of 

 selection, although in most cases where species in a 

 state of nature are concerned, the process of degener- 

 ation has been both hastened and intensified by the 

 super-added influence of the reversal of selection. In 

 the next volume I shall have occasion to recur to 

 this distinction, when it will be seen that it is one of 

 no small importance to the general theory of descent. 



We may now proceed to consider certain mis- 

 conceptions of the Darwinian theory which are largely, 

 not to say generally, prevalent among supporters of 

 the theory. These misconceptions, therefore, differ 

 from those which fall to be considered in the next 

 chapter, i. e. misconceptions which constitute grounds 

 of objection to the theory. 



Of all the errors connected with the theory of 

 natural selection, perhaps the one most frequently met 

 with especially among supporters of the theory is 

 that of employing the theory to explain all cases of 



