242 THE INDUCTIONS OF BIOLOGY. 



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 the inferences they draw from simple 

 and perpetually- repeated observations ; and when we find 

 that the inference arrived at, and handed down from genera- 

 tion to generation of these deeply-interested observers, has 

 become 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 

 conviction that minor peculiarities of organization are in- 

 herited 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 in- 

 ferior stocks. Citing the highest authorities respecting the 

 effects of breeding from animals having certain superiorities, 

 with the view of propagating those superiorities, Mr Darwin 

 writes : — " Youatt, who was probably better acquainted with 

 the works of agriculturists than almost any other individual, 

 and who was himself a very good judge of an animal, speaks 

 of the principle of selection as ' that which enables the agri- 

 culturist not only to modify the character of his flock, but to 

 change it altogether. It is the magician's wand, by means of 

 which he may summon into life whatever form and mould he 

 pleases/ " Lord Somerville, speaking of what breeders have 

 done for sheep, says : — " It would seem that they had chalked 

 upon a wall a form perfect in itself and then given it exist- 

 ence." That most skilful breeder, Sir John Sebright, used to 

 say, with respect to pigeons, that "he would produce any 

 given feather in three years, but it would take him six years 

 to obtain head and beak." In all which statements the 

 tacit assertion is, that individual traits are bequeathed 

 from generation to generation ; and that when they are 

 not brought into conflict with opposite traits, they may be 



