416 STERILITY OF HYBRIDS. 



ties, should grow less and less; and those mongrels 

 should acquire, by degrees, the sterility characteristic 

 of hybrids : 



Furthermore; as it is generally characteristic of in- 

 dividuals of the same species, to be fertile with each 

 other, the fertility of the individuals of each variety, 

 when bred, inter se, should grow greater, and greater, 

 in proportion as the variety, to which they belonged, 

 diverged : 



Long continued domestication, or this divergence of 

 character which according to Darwin evolves the 

 varieties into species, should eliminate any tendency 

 to sterility, with the individuals of the same variety ; 

 and eliminate any tendency to fertility, with the mon- 

 grels between such varieties : 



The individuals of different varieties should grow 

 mutually sterile, and the individuals of the same va- 

 riety, should grow more fertile: 



The greater the structural differences, between varie- 

 ties, the more sterile should be their mongrels. 



Such are not the facts. The facts are diametrically 

 at variance with those required by Darwin's hypothesis. 



On page 162, Vol. ii, Animals and Plants, &c, he 

 says : 



"It deserves especial attention, that mongrel ani- 

 mals and plants which are so far from being sterile, 

 that their fertility is often actually augmented, have, as 

 previously shown, their size, hardihood and constitu- 

 tional vigor generally increased." 



Again, he says, p. 326, Origin of Species : 



"Varieties, however much they differ from each 



