STUDIES IN HUMAN HEREDITY 



311 



Chart, figure 40, gives a four-generation historj^ of carcinoma. Nodules 

 appeared on face, fingers and toes, as indicated. A was married three 

 times, once -nithout issue. With one vnie he had five affected and two 

 normal children; with another ■ndfe all six" children were normal. A's 

 pedigree seems to indicate that cancer is dominant to the normal condition. 

 There are other instances in which a pathologic condition appears domi- 

 nant to the normal. Susceptibility in some cases seems dominant to im- 

 munity— e.g., wheat rust in the plant kingdom. But whether immunity 

 means the presence of an inhibitory factor, or the absence of an inducing 

 factor; likewise whether susceptibility be due to the presence of a predis-' 

 posing factor, or the absence of an inhibitory factor, remains obscure. 



■fate. 



X 



A 



o 



o 



-© 



iace 



666666 



_^__^_^^__^ (secoy7^ set of c(,il4ren) 



64i6-T-o 



i46c!)666 666iti6b66. 



Fig. 40 Carcinoma. 



Moreover, there are probably grades of susceptibility and resistance, 

 as the family history in question indicates. "Grades" probably involves 

 a complexity of factors. The fact that with one wife A had five carcino- 

 matous and two normal, and with the other all six normal offspring, gives 

 further evidence of "grades," or reversal or imperfection of dominance. 

 Furthermore, the affected fraternity of the fourth generation indicates the' 

 same. We are dealing here with apparently similar parental germinal 

 constitutions, and with the same number of offspring as in the carcino- 

 matous childship of generation three; but here five out of seven are normal, 

 whereas, there five out of seven were abnormal. The normal fourth 

 generation childship contains nine individuals. What seems clearly indi- 

 cated in this family history is that carcinoma has a hereditary aspect; 



