Principles of Heredity 113 



of heredity and species Evolution, as we should now say- 

 by the only sound method experimental breeding to 

 leave out of consideration almost the whole block of 

 evidence collected in Animals and Plants Darwin's finest 

 legacy as I venture to declare was unfortunate on the 

 part of any exponent of Heredity, and in the writings of a 

 professed naturalist would have been unpardonable. But 

 even as modified in 1900 the Law of Ancestral Heredity 

 is heavily over-sparred, and any experimental breeder could 

 have increased Pearson's list of unconformable cases by as 

 many again. 



But to return to Professor Weldon. He now repeats 

 that the Law of Ancestral Heredity seems likely to prove 

 generally applicable to blended inheritance, but that the 

 case of alternative inheritance is for the present reserved. 

 We should feel more confidence in Professor Weldon's 

 exposition if he had here reminded us that the special 

 case which fitted Gal ton's Law so well that it emboldened 

 him to announce that principle as apparently " universally 

 applicable to bi-sexual descent" was one of alternative 

 inheritance namely the coat-colour of Basset-hounds. 

 Such a fact is, to say the least, ominous. Pearson, in 

 speaking (1900) of this famous case of Galton's, says that 

 these phenomena of alternative inheritance must be treated 

 separately (from those of blended inheritance)*, and for 

 them he deduces a proposed "law of reversion" based of 

 course on ancestry. He writes, "In both cases we may 

 speak of a law of ancestral heredity, but the first predicts 

 the probable character of the individual produced by a 



* " If this be done, we shall, I venture to think, keep not only our 

 minds, but our points for observation, clearer ; and further, the failure 

 of Mr Galton's statement in the one case will not in the least affect 

 its validity in the other." Pearson (32), p. 143. 



B. 8 



