176 NATURAL INHERITANCE. [chap. 



marriages, which appears to be very small when 

 statistically discussed, but of whose occasional severity 

 most persons have observed examples. 



I interpret these results as showing that consumption 

 is largely acquired, and that the hereditary influence of 

 an acquired attack is small when there is no accom- 

 panying " malformation." This last phrase is intended 

 to cover not only a narrow chest and the like, but what- 

 ever other abnormal features may supply the physical 

 basis upon which consumptive tendencies depend, and 

 which I presume to be as hereditary as any other 

 malformations. 



Severely -tainted Fraternities. — Pursuing the matter 

 further, I selected those fraternities in which consump- 

 tion was especially frequent, and in which the causes of 

 the deaths both of the Father and of the Mother were 

 given. They were 14 in number, and contained be- 

 tween them a total of 102 children, of whom rather 

 more than half died before the age of 40. Though 

 records of infant deaths were asked for, I doubt if 

 they have been fully supplied. As 102 differs little 

 from 100, the following figures will serve as per- 

 centages : 42 died of actual consumption and 11 others 

 of lung disease variously described. Only one case 

 was described as death from heart disease, but weakness 

 of the heart during life was spoken of in a few cases. 

 The remaining causes of death were mostly undescribed, 

 and those that were named present no peculiarity worth 

 notice. I then took out the causes of death of the 



