LAWS OF HEREDITY. 11 



*' sport." Hence the failure of an individual to reproduce features that are pecii- 

 liar to itself, or of a pair of individuals, distinguished for the same peculiarity, 

 to transmit it to the otfspring, should excite no surprise in the mind of the 

 hreeder. Heredity transmits with certainty only -what has hecome a fixed 

 character in the race. Sports, accidental variations, and individual peculiarities, 

 only occur in opposition to this law, and their transmission is at best uncer- 

 tain. Heredity may be depended on to govern the general characteristics 

 which determine the species, and the less general ones, which distinguish the 

 breed, but when we come to individual characteristics, which have never 

 acquired a general character in the ancestry, it frequently fails. In short, the 

 transmission of the greater share of all the characteristics is a thing of uni- 

 versal occurrence, but their transmission in toto is an ideal conception that is 

 . never realized ; and only in proportion as the ancestry has assumed a fixed 

 and unvarying type, do we find this ideal of the effect of heredity approxi- 

 mated. 



That peculiarity called atavism, or reversion, so often noticed in our 

 domesticated animals, and which has so frequently set at naught the calcu- 

 lations of the breeder, has often been quoted as an illustration of the failure of 

 the law of heredity; but it is, in fact, only a tribute to its power. By selec- 

 tion, change of climate or of nutrition, or by crossing, or by all of these means 

 combined, we may succeed in obliterating certain well-defined characteristics, 

 and in modifying a given type, until the new form or character that we have 

 created will, in its turn, be transmitted with reasonable certainty ; but suddenly 

 the germ that has lain dormant for so many generations asserts itself, and, 

 greatly to our surprise, the characteristics of the original stock will reappear. 

 These cases of reversion most frequently occur when cross-breeding is resorted 

 to. The counter currents of hereditary influence, which are by this means 

 brought into contact, having a common origin, awaken to life the germ which 

 has for generations been a silent factor in each of the newly-created breeds, 

 and enables it to again assume control of the organism. 



In addition to the general and well-defined operation of the laws of heredity 

 to which we have alluded, its operations in the transmission of individual 

 characteristics, although not clearly defined, and never to be depended upon, 

 are often wonderful. The son is frequently, in some respects, the exact dupli- 

 cate of the father, and the daughter of the mother. Sometimes a peculiarity 

 which belonged to the grandsire lies dormant in the son, but crops out as 

 strong as ever in the second or third generation. Again : we find peculiarities 

 transmitted from father to daughter, and from mother to son, and even 

 especial sexual characteristics transmitted by the father through a daughter 

 to a grandson, or by the mother through a son to a granddaughter ; but it is 

 worthy of remark, that in no case are all the peculiarities of any one individ- 

 ual transmitted. Indeed, it would be strange were it otherwise, because each 

 individual is the joint product of two other individuals, each endowed 

 with peculiarities of its own; and that each should transmit itself as an 

 entirety is' absolutely impossible. Neither do we find in the individual so 

 produced a blending of these peculiarities in exact proportion — as one might 

 theoretically argue would be the result were the parents of equally well estab- 



