CROSSING AND CLOSE-INTERBREEDING. 23 T 



to distinct varieties, and partially even to species. In 

 the latter case, though size is often gained, fertility is 

 lost." 



Even if Darwin had perceived, that the contribu- 

 tion, to the offspring, by either parent, of a character 

 which answered to the part deficient in the other 

 parent, could furnish an explanation of the good re- 

 sulting from crossing; such a solution upon the hypoth- 

 esis of evolution, would not be so satisfactory, as it 

 is upon the theory of Reversion. For, upon the 

 theory of Reversion, the characters, supplied to the 

 offspring, are characters which were once lost, the 

 regain of which, is needed to secure perfection ; where- 

 as, upon the theory of evolution, there is no explana- 

 tion, of why the mere addition of characters, should 

 bring with it, increased fertility : seeing, that species, 

 with a small number of characters, are generally as 

 fertile, and sometimes more so, than species, with a 

 development greatly more complex. Neither would 

 there be any assignable reason, upon Darwin's theory, 

 why, where there was, in each parent, a positive peculi- 

 arity, and a defective character, the defective character 

 should not be prepotent over the positive character, 

 and evil result, in the offspring, through the defects 

 in either, sinking the corresponding, positive develop- 

 ments in the other parent. 



The reason, why good, instead of evil, results, when 

 two individuals, dissimilarly defective, are crossed, is r 

 because, in the defective points of each, the power of 

 reversion exists, ever ready to assert itself, under con- 

 ditions in anywise favorable ; and, this capacity joins 

 21 



