XL] SPECIFIC GENESIS. 267 



ment, and perhaps generally monstrosities of some sort 

 are the result of such affections of the embryo. To the 

 second category belong cases of hybridism, of cross breed, 

 and in all probability the new varieties and forms, such as 

 the memorable one of the black-shouldered peacock. In 

 these cases we do not have abortions or monstrosities, but 

 more or less harmonious forms often of great functional 

 activity, endowed with marked viability and generative 

 prepotency, 1 except in the case of hybrids, when we often 

 find even a more marked generative impotency. 



It seems probable therefore that new species may arise 

 from some constitutional affection of. parental forms an 

 affection mainly, if not exclusively, of their generative 

 system. Mr. Darwin has carefully collected 2 numerous 

 instances to show how excessively sensitive to various 

 influences this system is. He says : 3 " Sterility is inde- 

 pendent of general health, and is often accompanied by 

 excess of size, or great luxuriance," and " No one can tell, 

 till he tries, whether any particular animal will breed 

 under confinement, or any exotic plant seed freely under 

 culture." Again, " When a new character arises, whatever 

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

 least in a temporary and sometimes in a most persistent 

 manner." 4 Yet the obscure action of conditions will alter 



1 In the "Descent of Man," vol. i. p. 223, the following passage 

 occurs : " When any character has suddenly appeared in a race or species 

 as the result of a single act of variation " .... " and this race is crossed 

 with another not thus characterised, the characters in question do not 

 common!}*- appear in a blended condition in the young, but are transmitted 

 to them either perfectly developed or not at all." 



2 See especially " Animals and Plants under Domestication," vol. ii. 

 chap, xviii. 



3 "Origin of Species," 5th edition, pp. 323, 324. 



4 "Animals and Plants under Domestication," vol. ii. p. 2. 



