HEREDITY 



3. When hybrids are paired with albinos, half the young produced 

 resemble their albino parent, half resemble their hybrid parent. This result 

 is in accord with Mendel's theory. 



Darbishire adds : "There is no evidence that any individuals 

 which could be properly described as ' pure dominants' or * pure 

 recessives ' exist among the whole series produced." 



The reciprocal cross. In Mendel's experiments generally recip- 

 rocal crosses, according to all accounts, gave identical results. 

 We know that as a general principle this does not always hold. 

 For example, the common mule, which is the product of the 

 male ass and the female horse, is said to be quite different from 

 its reciprocal cross, the hinny, which is the product of the male 

 horse and the female ass. The one is valuable, while all horse- 

 men seem to agree that the other is lazy and worthless. How 

 much of this is fact and how much is tradition is doubtless some- 

 what uncertain. 



SECTION XIV THE LAW OF ANCESTRAL HEREDITY 



We have abundant evidence that in a large sense the off- 

 spring is the product of something more than the immediate par- 

 ents. The fact of resemblance to ancestors more remote than the 

 parents, and the additional fact that successive offspring of the 

 same parents are not alike but form an array not very different 

 from that of offspring in general, these facts alone show us 

 either that the ancestors beyond the parents contribute something 

 to the offspring, or which is the same thing that characters 

 are made up out of elements that are handed down from parent 

 to offspring and from which many and various combinations 

 are possible in succeeding generations and even in the same 

 generation. 



The interesting question now arises, How are these hereditary 

 influences back of an individual distributed among his ancestors 

 of various degrees of consanguinity, from his immediate parents 

 backward ? 



Manifestly the answer to this question is beset with many 

 difficulties. We could secure a rough approximation by working 

 out the coefficient of heredity between offspring and parent, 



