CROSSING AND CLOSE-INTERBREEDING. 225 



ment of either, and of both, of the sexual elements, it is 

 proper to reserve the full treatment of the question until 

 the phenomena of generation engage our attention. 



A case, illustrative of the rule, that prepotency is due, 

 frequently, to the long maintenance of a given ratio of 

 development, is to be found in the following remark of 

 Darwin (p. 89, Vol. ii, Animals and Plants, &c.) : 



"A purely bred form of either sex, in all cases in 

 which prepotency does not run more strongly in one 

 sex than the other, will transmit its character, with pre- 

 potent force over a mongrelized and already variable 

 form." 



There is another reason for this phenomenon, besides 

 the fact, that the prepotent form has long been per- 

 sistent in its peculiar type. The reason is an obvious 

 one, upon the theory of reversion. To Darwin, this, 

 with all of the other facts on breeding, is inexplicable. 

 Having vitiated his theory at the start, by leaving the 

 question of the cause of variation, or improvements, un- 

 resolved, it is incompetent to the; explanation of any of 

 the phenomena. 



In the "mongrelized and already variable form," all 

 of the characters of its species, or the major portion of 

 them, are striving to revert to the original, full develop- 

 ment, proper to the perfect type. No one, of the char- 

 acters, is predominant; or, if there be one or more 

 advanced in development, it is very little in the ascend- 

 ant. When crossed with "a purely bred form," which 

 has (especially when it belongs to a widely divergent 

 variety), one character, of its species, most decidedly 

 developed, this "purely bred form" becomes prepo- 

 20 



