304 THE INDUCTIONS OF BIOLOGY. 



the characters of neighbouring peoples. Nay, even between 

 races so closely allied as the Scotch Celts, the Welsh Celts, 

 and the Irish Celts, appreciable differences of form and nature 

 have become established. 



The fact that sub-species and sub-sub-species thus exem- 

 plify the general law of inheritance which shows itself in the 

 perpetuation of ordinal, generic, and specific peculiarities, is 

 strong reason for the belief that this general lay is unlimited 

 in its application. This has the support of still more special 

 evidences. They are divisible into two classes. In the one 

 come cases where congenital peculiarities, not traceable to 

 any obvious causes, are bequeathed to descendants. In the 

 other come cases where the peculiarities thus bequeathed are 

 not congenital, but have resulted from changes of functions 

 during the lives of the individuals bequeathing them. We 

 will consider first the cases that come in the first class. 



§ 81. Note at the outset the character of the chief testi- 

 mony. Excluding those inductions that have been so fully 

 verified as to rank with exact science, there are no inductions 

 so trustworthy as those which have undergone the mercantile 

 test. When we have thousands of men whose profit or loss 

 depends on the truth of their inferences from perpetually- 

 repeated observations ; and when we find that their inferences, 

 handed down from generation to generation, have generated an 

 unshakable conviction; we may accept it without hesitation. 

 In breeders of animals we have such a class, led by such 

 experiences, and entertaining such a conviction — the convic- 

 tion that minor peculiarities of organization are inherited as 

 well as major peculiarities. Hence the immense prices given 

 for successful racers, bulls of superior forms, sheep that have 

 certain desired peculiarities. Hence the careful record of 

 pedigrees of high-bred horses and sporting dogs. Hence the 

 care taken to avoid intermixture with inferior stocks. As 

 quoted by Mr. Darwin, Youatt says the principle of selection 

 '^ enables the agriculturist not only to modify the character 



