78 THE GENESIS OF SPECIES. [CHAP. 



has elsewhere 1 pointed out, there is a certain similarity 

 of the upper cutting teeth, or incisors. 



Now these correspondences are the more striking when 

 we bear in mind that a similar dentition is often put to 

 very different uses. The food of different kinds of apes is 

 very different, yet how uniform is their dental structure ! 

 Again, who, looking at the teeth of different kinds of bears, 

 would ever suspect that one kind was frugivorous, and 

 another a devourer exclusively of animal food ? 



The suggestion made by Professor Huxley was therefore 

 one which had much to recommend it to Darwinians, 

 though it has not met with any notable acceptance, and 

 though he seems himself to have returned to the older 

 notion, namely, that the pouched-beasts, or marsupials, 

 are a special ancient offshoot from the great mammalian 

 class. 



But whichever view may be the correct one, we have in 

 either case a number of forms similarly modified in har- 

 mony with surrounding conditions, and eloquently pro- 

 claiming some natural plastic power, other than mere 

 fortuitous variation with survival of the fittest. If, how- 

 ever, the reader thinks that teeth are parts peculiarly 

 qualified for rapid variation (in which view the author 

 cannot concur), he is requested to suspend his judgment 

 till he has considered the question of the independent 

 evolution of the highest organs of sense. If this seems to 

 establish the existence of some other law than that of 

 " Natural Selection," then the operation of that other law 

 may surely be also traced in the harmonious co-ordinations 

 of dental form. 



The other difficulty, kindly suggested to ine by the 



1 "Journal of Anatomy and Physiology" (1868), vol. ii. p. 139. 



