li4 COMMON MODES OF INHERITANCE 



tency " ; and it may be that the father is " prepotent " in regard 

 to some of the characters and the mother in regard to others. 

 A negro in Berlin had by a white woman seven daughters who 

 were markedly mulatto, and four sons who were white ; the 

 inheritance was " crossed," but other cases forbid us from 

 making any generalisation. 



It must be carefully kept in view that where the expression of the 

 inheritance markedly follows one parent, it does not in the least 

 follow that the corresponding contributions from the other parent 

 have been lost. It may be that the latter will reappear in the next 

 generation, having simply remained latent in the custody of the 

 germ-cells. And again, there are cases on record where the young 

 boy resembled the mother and the young girl the father ; but as they 

 grew up, the likeness was reversed i.e. resemblances formerly ob- 

 scure became conspicuous. Such cases seem to warrant our insist- 

 ence on the distinction between the inheritance and the expression 

 of the inheritance. 



// must be carefully borne in mind that what we describe as a case 

 of exclusive inheritance may be the first step in Mendelian inherit- 

 ance. When a parent with a dominant unit character mates with one 

 having a corresponding unit character recessive the offspring all show 

 the dominant character. 



5. P articulate Inheritance 



In many cases it may be seen that the peculiarities of the two 

 parents do not blend, but are separately expressed in different 

 parts of the same organ or system. The combination is, as it 

 were, too coarse-grained to be called a mixture or a blend. This 

 is termed p articulate inheritance. 



A familiar instance is a piebald foal the progeny of a dark- 

 coloured sire and a light-coloured mare. The paternal hair is 

 seen in some parts, the maternal hair in other parts. " Eye- 

 colour is generally exclusive, but we get one or two cases per 

 thousand in man, in which either the two irises differ in colour, 



