196 ADAPTATION 



ceneus, elsewhere with two maxillary teeth, is 

 varying in the old-fashioned way towards a form 

 whose entire maxillary is covered with teeth, i.e. 

 it is varying to become a Hemibrycon. Of 

 thirty-five specimens there are nine -with two 

 teeth, two with three teeth, five with four teeth, 

 five with five teeth, five with six teeth, five with 

 seven teeth, three with eight teeth, and one with 

 nine teeth in the maxillary. No doubt there are 

 some who will claim that these are really muta- 

 tions, not variations, and I am perfectly willing 

 that they should put this balm upon their preju- 

 dices. 



The nature of the progressive degeneration of 

 the eyes of blind fishes argues also against the uni- 

 versahty of the origin of adaptations by muta- 

 tion. The degeneration of the eyes of such fishes 

 is a continuous process. The eyes of individuals 

 during their lifetime undergo a continuous de- 

 generative modification leading sometimes to the 

 entire elimination of the eye in the old. The 

 retrogressive changes begin in ever earher stages 

 of the ontogeny. The differences between indi- 

 viduals are so slight as to exclude the possibility 

 of personal selection, without which either muta- 

 tion or Natural Selection is incapable of produc- 

 ing results. 



There is no evidence that mutation has had 

 any more to do with the production of degener- 

 ate eyes than special creation, and we can not 

 even imagine how the degenerate eyes might have 



