130 Law of Ancestral Heredity [en. 



remain exactly in the same condition as at their first appear- 

 ance, and the selection has merely resulted in a reduction of 

 their number. If the purples were saved individually and 

 their seeds separately sown, it would immediately be seen 

 that some were pure, giving purples only, and that others 

 were impure, the latter consisting of the various gametic 

 types with which we are now familiar. 



Since then we know that ancestral composition does not 

 decide the constitution of such a population, and since 

 individuals of identical parentage may have most divergent 

 genetic properties, it is absurd to attempt to trace the 

 workings of any Law of Ancestral Heredity among these 

 phenomena 



The suggestion that methods based on unanalysed 

 statistics have scientific value in the study of heredity can 

 scarcely mislead those who have examined the facts. 

 Professor Pearson and others committed to these methods 

 have of late defended their position by arguing that there is 

 no fundamental incompatibility between Laws of Ancestral 

 Heredity and the conclusions of Mendelian analysis. The 

 matter would not be worth notice were it not that the same 

 proposition is being freely repeated by several writers seek- 

 ing some convenient shelter of neutrality*. It is to be 

 observed however that the supposition of an underlying 

 harmony between Mendelian and biometrical results was 

 not put forward by the biometricians until every possible 

 means of discrediting the truth of Mendelian facts had been 

 exhausted. Those attacks having failed, we are asked to 

 observe that the Law of Ancestral Heredity was meant as 

 a statement of a statistical consequence, and is not concerned 

 with physiological processes. Mr Galton's views on this 

 point are well shown in the following passage in which he 

 explicitly appeals to the physiological process of gameto- 

 genesis as apparently occurring in the way which his Law 

 requires. For in introducing the Law as applicable to 

 Bassets (125, p. 403) he wrote: 



" It should be noted that nothing in this statistical law 

 contradicts the generally accepted view that the chief, if not 



* See for example Darbishire, Mem. Manchester Lit. and Phil. Soc. 

 1905, No. 6 and 1906, No. n; and Professor J. A. Thomson, Heredity, 

 passim. 



