STUDIES IN HUMAN HEREDITY 



309 



factor, supposing the first-generation male to be heterozygous dominant 

 and the female homozj^gous recessive.* 



',i.nfan cy 



Fig. 37 Pulmonart Tuberculosis. 



Case, figure 37, gives a two-generation tuberculosis history, and also 

 indicates that the tuberculosis factor is recessive to the normal condition. 





-D 





Fig. 38 Pulmonary Tuberculosis. 



Case, figure 38, again gives a three-generation history and the same evi- 

 dence with respect to the recessiveness of the pathologic condition. 



Case, figure 39, gives a fairly complete four-generation history. Judg- 

 ing from the progeny we are undoubtedly justified in regarding the mother, 

 C — the cause of whose death is unknown — as also tubercular (pure reces- 

 sive?). No information could be secured about fraternity A; fraternity B, 

 with one exception, was said to be "living and well." Two individuals of 

 this fraternity have had a child each die of tuberculosis. 



Contrary to the opinion frequently heard, no evidence appears among 

 these few cases that the male parent is hereditarily prepotent over the 

 female in the matter of transmitting tubercular diathesis. 



* Explanation of symbols of pedigree charts: d, died at the age indicated; s, sick 

 for the time indicated; c, cured for the time indicated; d.i., died in infancy. 



