174 DARWINIANA. 



bridism, and that their variation in Nature is not es- 

 sentially different from much that occurs in domesti- 

 cation, and, in the long-run, probably hardly less in 

 amount, we. could show if our space permitted. 



As to the sterility of hybrids, that can no longer be 

 insisted upon as absolutely true, nor be practically 

 used as a test between species and varieties, unless we 

 allow that hares and rabbits are of one species. That 

 such sterility, whether total or partial, subserves a pur- 

 pose in keeping species apart, and was so designed, we 

 do not doubt. But the critics fail to perceive that 

 this sterility proves nothing whatever against the de- 

 rivative origin of the actual species ; for it may as 

 well have been intended to keep separate those forms 

 which have reached a certain amount of divergence, as 

 those which were always thus distinct. 



The argument for the permanence of species, drawn 

 from the identity with those now living of cats, birds, 

 and other animals preserved in Egyptian catacombs, 

 was good enough as used by Cuvier against St.-Hi- 

 laire, that is, against the supposition that time brings 

 about a gradual alteration of whole species; but it 

 goes for little against Darwin, unless it be proved that 

 species never vary, or that the perpetuation of a vari- 

 ety necessitates the extinction of the parent breed. 

 For Darwin clearly maintains what the facts warrant 

 that the mass of a species remains fixed so long as 

 it exists at all, though it may set off a variety now and 

 then. The variety may finally supersede the parent 

 form, or it may coexist with it ; yet it does not in the 

 least hinder the unvaried stock from continuing true 

 to the breed, unless it crosses with it. The common 



