84 Life and Letters of Francis Galton 



rightly interpreted lead to no "universal regression," still less to an argument 

 that "variations proper" cannot be the subject of selection and the formation 

 of new breeds. 



This does not prove that "variations proper" have been the basis of 

 evolution, but it removes Gal ton's chief reason for belief in evolution by 

 discontinuity, that is by sports or mutations. The law of "universal regres- 

 sion " — over which Galton undoubtedly stumbled — is only true when we 

 neglect ancestry beyond the parents and suppose mating at random, but 

 these are not the conditions which exist when intense selection is taking place 

 and the selected interbreed. 



Having prefaced Galton's views on Discontinuity with some criticism, 

 which I think is needful, of his theory of regression, we may turn to his 

 paper on "Discontinuity in Evolution," which was published in Mind, Vol. in, 

 N.S. pp. 362-372, July, 1894. Galton begins by saying that students of the 

 laws of variation need not be disheartened by the impossibility of learning 

 what is the cause of variation. Galton, who, as we have seen, believed in 

 individuality in the numerous germ cells of an organism, and that germ cells 

 were subject to selection, found no difficulty in attributing variation to the 

 effect of interacting germinal elements*. He considered that the actual cause 

 of any particular variation might be put on one side by those who study the 

 degree and character of variation generally. 



We are next provided with a definition of race based upon the idea of a 

 typical centre of regression. As I understand him A and B are two different 

 races, if the offspring of the members of A and the offspring of the members 

 of B regress to two different centres of regression. But how can we practically 

 demonstrate this ? If we take the offspring of a pair of individuals of race A, 

 the degree in which they differ from their parental mean will depend upon 

 the long line of ancestry of those parents (to adopt Galton's own views); if 

 the parents were relatively small in stature, say, for their ancestry, the 

 offspring average may exceed the parental stature; if they were relatively 

 tall, the offspring average may fall short of the parental. If we choose such 

 a large number of parents of given statures, that we may assume the 

 ancestors of the parents have for average value that of the general popula- 

 tion, then the offspring average will regress to the population mean, and 

 should we know the regression coefficient accurately, this will provide the 

 population mean or " typical centre of regression." Similarly we might 

 determine the typical centre of the race B, and ascertain whether the two 

 centres were or were not significantly different. But I cannot see that this 

 is any more than inquiring whether the populations A and B have different 



. * I must confess to feeling it extremely difficult to accept the view that the population of 

 germ cells belonging to an individual organism are like atoms, identical in character, and 

 have a germinal capacity defined by absolutely the same formula. Such a population of germ 

 cells is, if parasitical, still an organic population, and one continually in a state of reproduction 

 and change. No other organic population that we know of is without variation among its 

 members, and I find it extraordinarily hard to believe that it is a matter of complete indiffer- 

 ence which individual spermatogonium of an organism is the ultimate source for fertilisation 

 of an individual ovum of a second organism. 



