THE ORIGIN OF SPECIES. 29 



great pliilosoplier of liorticulture, that variability under 

 domestication is somehow connected with excess of 

 food. He regards the unknown cause as acting chiefly 

 upon the reproductive system of the parents, which 

 system, judging from the effect of confinement or cul- 

 tivation upon its functions, he concludes to be more 

 susceptible than any other to the action of changed con- 

 ditions of life. The tendency to vary certainly appears 

 to be much stronger under domestication than in free 

 J^ature. But we are not sure that the greater variable- 

 ness of cultivated races is not mainly owing to the 

 far greater opportunities for manifestation and accu- 

 mulation — a view seemingly all the more favorable to 

 Mr. Darwin's theory. The actual amount of certain 

 changes, such as size or abundance of fruit, size of 

 udder, stands of course in obvious relation to supply 

 of food. 



Really, we no more know the reason why the pro- 

 geny occasionally deviates from the parent than we do 

 why it usually resembles it. Though the laws and 

 conditions governing variation are known to a cer- 

 tain extent, those governing inheritance are appar- 

 ently inscrutable. " Perhaps," Darwin remarks, '^ the 

 correct way of viewing the whole subject would be, to 

 look at the inheritance of every character whatever as 

 the rule, and non-inheritance as the anomaly." This, 

 from general and obvious considerations, we have long 

 been accustomed to do. ]lS^ow, as exceptional instances 

 are expected to be capable of explanation, while ulti- 

 mate laws are not, it is quite possible that variation 

 may be accounted for, while the great primary law of 

 inheritance remains a mysterious fact. 



