IS4 THE FOUNDATIONS OF ZOOLOGY 



statistics are proverbial ; and it is not impossible that Galton's 

 data may fail to cover all the ground which they should in order 

 to prove his general conclusions. 



One of these generahzations is so far-reaching that it must, if 

 well founded, lead to fundamental change in our view of the 

 origin of species. 



According to Darwin and Wallace, specific identity in living 

 things is the outcome of the extermination, in the struggle for 

 existence, of the individuals which depart too widely from that 

 "type" which is, on the whole, the best adapted to existing condi- 

 tions. As these conditions change, the type is also slowly modi- 

 fied through a change in the standard of extermination. Accord- 

 ing to this view, the type is the outcome of the statistical " law 

 of error " or the deviation from the mean, that holds good in the 

 environment; and while the "events" are properties of the organ- 

 ism, the type is fixed by the external world, and not by any- 

 thing in the organism itself. 



Galton holds that specific identity is not due to the process of 

 extermination, but to " organic stability." As I understand him, 

 he holds that this fills up the gaps made by extermination, and 

 thus keeps the type intact. This " principle of stability," which 

 is held to result in the persistency of types, is said to be quite 

 independent of selection. " Genera and species may be formed 

 without the slightest aid from either natural or sexual selection." 

 " Organic stability is the primary factor by which the distinctions 

 between genera are maiptained." Galton holds, furthermore, not 

 only that specific stability is independent of selection, but that 

 selection is "scarcely competent" to effect a change of type "by 

 favoring mere varieties" — that is, the ordinary* slight differences 

 between individuals ; and that it is only when a " sport " has 

 made its appearance, only when the type has actually changed, 

 that selection can exert any influence. According to this view 

 the agencies which cause sports are the real causes of the 

 mutation of species, and natural selection can do no more than to 

 exterminate disadvantageous sports, and thus favor advantageous 

 ones. The "organic stability" to which so much is attributed is 

 held to be due to the fact that the child inherits in part from its 

 parents, and in part from more remote ancestors ; and since the 



