Principles of Heredity 185 



the parent except in so far as it may give us a guide as to 

 the nature of its gametes. 



This indication, if taken in the positive sense as was 

 sufficiently shown in considering the significance of the 

 "mule" form or "hybrid-character" we now know may 

 be absolutely worthless, and in any unfamiliar case is very 

 likely to be so. Mendel has proved that the inheritance 

 from individuals of identical ancestry may be entirely 

 different : that from identical ancestry, without new 

 variation, may be produced three kinds of individuals 

 (in respect of each pair of characters), namely, individuals 

 capable of transmitting one type, or another type, or both : 

 moreover that the statistical relations of these three classes 

 of individuals to each other will in a great number of cases 

 be a definite one : and of all this he shows a complete 

 account. 



Professor Weldon cannot deal with any part of this 

 phenomenon. He does little more than allude to it in 

 passing and point out exceptional cases. These he suggests 

 a study of ancestry will explain. 



As a matter of fact a study of ancestry will give little 

 guide perhaps none even as to the probability of the 

 phenomenon of dominance of a character, none as to the 

 probability of normal "purity" of germ-cells. Still less 

 mil it help to account for fluctuations in dominance, or 

 irregularities in "purity." 



Ancestry and Dominance. 



In a series of astonishing paragraphs (pp. 241-2) Professor 

 Weldon rises by gradual steps, from the exceptional facts 

 regarding occasional dominance of green colour in Telephone 

 to suggest that the wfiole phenomenon of dominance may be 



