vn] Basset Hounds 127 



and so on, the total heritage being thus reckoned as unity. 

 It will be observed that this scheme differs entirely from 

 those based on Mendelian principles, inasmuch as every 

 ancestor is, according to the Law of Ancestral Heredity, 

 supposed to have some effect on the composition of each 

 family in its posterity, and each recent progenitor is re- 

 garded as having a very sensible influence on these 

 numbers. 



Though no one with a knowledge of practical breeding 

 could entertain the supposition that Galton's Law had the 

 universality of application claimed for it, there was on the 

 other hand no doubt that the Law had successfully expressed 

 a variety of facts in which' no order at all had been pre- 

 viously detected. 



We have now to consider the meaning of this evidence 

 in the light of modern knowledge. At the time that 

 Galton's views were promulgated nothing was known of 

 segregation. The supposition that any individual, whatever 

 its own characters, was capable of carrying on and trans- 

 mitting to its posterity any of the characters exhibited by 

 its immediate progenitors, at all events, was generally 

 received without question by biologists. According to that 

 idea the number of classes of individuals differing in respect 

 of their ancestral composition and transmitting powers is to 

 be regarded as indefinitely large, whereas in all cases of 

 sensible allelomorphism the number of classes of individuals 

 is three only, two being homozygous and one heterozygous. 

 The difference between the two schemes is thus absolute 

 and irreconcileable. 



When Mendelian phenomena were first recognized it 

 was naturally supposed that some classes of cases would be 

 found to conform to the Mendelian scheme and others to 

 the Law of Ancestral Heredity. With the progress of 

 research however almost all the cases to which precise 

 analytical methods have been applied have proved to be 

 reducible to terms of Mendelian segregation ; and of those 

 which have not already been so elucidated some, we may 

 feel confident, if not all, will be eventually shown to be 

 governed by similar rules. In discussing aberrant pheno- 

 mena like those alleged in regard to the Bassets the first 

 question to be settled is whether the facts are correctly 



