44 HEREDITY 



change prior to the union of the male and female 

 gametes. For we have seen that one-half of the 

 nuclear chromatin of each gamete is thrown aside 

 prior to the fusion of the two nuclei. This obviously 

 corresponds exactly with Galton's assertion that the 

 two parents between them contribute one-half of the 

 total heritage of the offspring. Thus the facts of 

 nuclear change in the process of gametogenesis (i.e. 

 the formation of the gametes from their mother-cells) 

 as observed by the microscope in the case of various 

 very simple animals, precisely correspond with a 

 mathematical formula derived by Mr. Galton from 

 the study of the inheritance in man of such things as 

 "artistic faculty." Surely we are entitled to regard 

 Galton's Law as demonstrably true. 



Its importance can scarcely be overestimated. It 

 is the theoretical basis upon which Galton and 

 Pearson have constructed a whole series of important 

 conceptions that have already served the science of 

 heredity. It has been shown to be more comprehen- 

 sively true than even its discoverer recognised. It is 

 even found to survive the criticism passed upon it by 

 the recent experimental study of variation in plants 

 and other organisms. But whilst we freely recog- 

 nise the importance and value of this law and 

 its elaborations, we must not delude ourselves with 

 the idea that it leaves nothing to explain. In a 

 certain sense, perhaps, Galton's Law, as extended by 

 Pearson, may be said to " render the whole theory 

 of heredity simple, straightforward, and luminous " ; 

 but it is evident that the author of this opinion was, 

 for the moment, taking a very narrow view of the 

 problems involved in the means by which Galton's 



