212 Scientific Sophisms. 



the* transmutations hypothecated by Mr. Dar- 

 win, yet they do know the " insurmountable 

 barrier " that " Nature " has erected against the 

 change of species. 1 They know that the Lin- 

 naean maxim Species naturae opus rests on 

 foundations too broad and deep to be shaken by 

 casual excess o. statement, or semblance of per- 

 plexity. While mere varieties, as superficial 

 excursions from type are technically termed, are 

 never mutually infertile, animals of different 

 species are physiologically contrasted with such 

 varieties by reciprocal repugnance or punitive 

 sterility. The mastiff and the terrier freely 

 inter-breed ; not so the horse and the ass : the 

 mongrel dog is a parent ; the hybrid mule is 

 not And the hybrid individual perishes, at 

 genus immortale manet. For it is a funda- 

 mental axiom that animals incapable of common 

 off-spring cannot have sprung from common 

 ancestors. 



On this head therefore, the evidence against 

 Mr. Darwin's theory of the Origin of Species is 

 overwhelming ; and no one knows this better 

 than Mr. Huxley himself. When therefore he 

 tells us that he adopts Mr. Darwin's hypothesis, 

 " subject to the production of proof that physio- 

 logical species may be produced by selective 

 1 Vide Appendix, Note C 



