SPECIAL CASES OF SEX-INHERITANCE 239 



ruination in man is found in the heredity of sex-linked 

 characters. 



The following cases may well serve to illustrate 

 some of the better ascertained characters. ~ The tables 

 are taken from Davenport's book on "Heredity in 

 Relation to Eugenics." The squares indicate males, 

 affected males are black squares^- the heavy circles indi- 

 cate females, that are supposed to carry the factors, but 



FIG. 112. Nine banded Armadillo. Embryonic blastocyst that has 

 four embryos on it, two of which are seen in figure. (After Newman and 

 Patterson.) 



such females do not exhibit the character themselves. 

 Solid black circles stand for affected females. 



Haemophilia appears in affected stocks almost ex- 

 clusively in males (Fig. 113). Such males, mating 

 with normal females, give only normal offspring, but 

 the daughters of such unions if they marry normal 

 males will transmit the disease to half of their sons. 

 Affected females can arise only when a haemophilious 

 male marries a female carrying haemophilia. If we 



