418 STERILITY OF HYBRIDS. 



diverge, they actually grow more fertile when they 

 cross, and that, by means of crossing, they eliminate 

 whatever tendency to sterility has been produced by 

 divergence, in their individuals ! 



So far from any difference, however great, inducing 

 sterility in the varieties, or in their mongrels, that cir- 

 cumstance it is, which gives the crossed breeds, and 

 their mongrels, the greatest increase of fertility! 

 This shows, that the structural differences of varieties, 

 are not being augmented into the greater differences 

 which distinguish species. Not only is the assump- 

 tion negatived completely, that varieties are " incipient 

 species," and that the sterility of species, and of their 

 hybrids, has been acquired, as the varieties grew, by 

 divergence, into species ; but the very converse obtains. 

 There are modifications slowly impressed upon the re- 

 productive systems of animals and plants, by the re- 

 duction or suppression of their characters, but those 

 modifications add additional force to the objection 

 founded on the sterility of hybrids. Independently 

 of this fact of the sterility of hybrids, and even though 

 the question of a limit to variation, had not been re- 

 solved, as it has been ; the fact that the varieties, of a 

 species, are incompetent to become distinct species, 

 would have been shown, by the phenomena of the 

 lessened fertility, and of the sterility of the individuals 

 of such a modified species. The explanation of varia- 

 tions, by means of reversion, disproves Darwin's theory. 

 The sterility of hybrids disproves Darwin's theory : 

 And, — to perfect the demonstration, — the phenomena 

 of the close-interbreeding and crossing of the indi- 



