THE LAWS OF Y ART ABILITY. 65 



to the primary cause which may have acted on the ovnles 

 or on the male element ; in nearly the same manner as 

 the increased length of the horns in the offspring from a 

 short-horned cow hy a long-horned bull, though appear- 

 ing late in life, is clearly due to the male element. 



Variation of If animals and plants had never been do- 

 Plants vol mesticated, and wild ones alone had been ob- 

 i, page 445. served, we should probably never have heard 

 the saying that "like begets like. " The proposition would 

 have been as self-evident as that all the buds on the same 

 tree are alike, though neither proposition is strictly true. 

 For, as has often been remarked, probably no two indi- 

 viduals are identically the same. All wild animals recog- 

 nize each other, which shows that there is some difference 

 between them ; and, when the eye is well practiced, the 

 shepherd knows each sheep, and man can distinguish a 

 fellow-man out of millions on millions of other men. 



The whole subject of inheritance is won- 

 derful. When a new character arises, what- 

 ever its nature may be, it generally tends to be inherited, 

 at least in a temporary and sometimes in a most persistent 

 manner. "What can be more wonderful than that some 

 trifling peculiarity, not primordially attached to the spe- 

 cies, should be transmitted through the male or female 

 sexual cells, which are so minute as not to be visible 

 to the naked eye, and afterward through the incessant 

 changes of a long course of development, undergone either 

 in the womb or in the egg, and ultimately appear in the 

 offspring when mature, or even when quite old, as in the 

 case of certain diseases ? Or, again, what can be more 

 ronderful than the well-ascertained fact that the minute 

 jvule of a good milking-cow will produce a male, from 



