180 HEREDITARY CHARACTERS 



In exclusive inheritance the offspring appears to take 

 entirely after the male or the female parent. Many 

 characters are often involved, and the offspring appears 

 to take after one parent only, in so far as there are any 

 differences between the parents. In these cases one parent 

 is said to be " absolutely prepotent." 



In particulate inheritance the characters of the parents 

 do not blend, but both are expressed. In some cases it 

 appears as though certain parts of the organism inherited 

 the male parent's peculiarity, other parts of the female 

 parent's with regard to the character. Probably the best- 

 known instance of this kind is a piebald horse, where the 

 different patches represent the two different colours inherited 

 from the parents, both being present though not blended. 

 Another less common example is the colour of the eyes. A 

 child generally inherits its eye colour from one parent only, 

 but in one or two cases in a thousand in man the two eyes 

 differ in colour, or one eye shows different patches of colour. 1 



In domesticated races those which are longest established 

 tend to be prepotent over newer races. A race which has 

 never been domesticated tends to be prepotent over a 

 domesticated race. It is generally supposed that very 

 inbred races are prepotent over races that have been less 

 inbred. When natural varieties or species are crossed, how- 

 ever, it is quite usual for the characters to be blended. 



There is no more doubt with regard to the fact that 

 some characters blend in inheritance, than there is that 

 some tend to segregate. Some extreme Mendelians would 

 have us believe that all inheritance is Mendelian, and 

 where blended inheritance seems to be the rule, they bring 

 forward what are apparently exceptions, and claim that 

 when we know more, the Mendelian phenomena will be 

 found universal. For instance, in the crossing of a black 

 and white race of men, a few obscure cases are brought 

 forward, and it is claimed that these show that the black 

 and the white colours in the two races segregate. It is quite 



1 Pearson, Grammar of Science, 2nd edition, London, 1900. 



