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 accompanying "malformation." This last phrase is intended to cover not only a narrow chest and the like, but whatever 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 consumption 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 between 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 percentages : 42 died of actual consumption and 11 others of lung disease variously described. Only one case was described is death from heart disease, but weakness of the heart during life was spoken of in a few cases. ,.'he 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