x.] DISEASE. 185 



at large, than there is in a group of consumptive 

 families. It would be quite fair to estimate the value 

 of n at least as low as 0'8. 



We have thus three values of n to try; viz. 1, 0'9, 

 and 0'8, of which the first is scarcely possible and the 

 last is much the more suitable of the other two. The 

 corresponding values of 073 divided by n, are + 0.73, 

 4- 0'81, and + 0'91. Eeferring to Table 8 we find the 

 Grades corresponding to those deviations to be 69, 71, 

 and 73. We should therefore expect 69, 71, or 73 

 per cent, of the Co-Fraternity to be non-consumptive, 

 according to the value of n we please to adopt, and 

 the complement to those percentages, viz. 31, 29, or 27, 

 to be consumptive. Observation (p. 173), gave the value 

 of 26 by one method of calculation, and of 28 by 

 another. 



Too much stress must not be laid on this coincidence, 

 because many important points had to be slurred over, 

 as already explained. Still, the prima facie result is 

 successful, and enables us to say that so far as this 

 evidence goes, the statistical method we have employed 

 in treating consumptivity seems correct, and that the 

 law of heredity found to govern all the different faculties 

 as yet examined, appears to govern that of consump- 

 tivity also, although the constants of the formula differ 

 slightly. 



Data for Hereditary Diseases. The knowledge of 

 the officers of Insurance Companies as to the average 

 value of unsound lives is by the confession of many of 



