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174   NATURAL INHERITANCE.   [CHAT.

consumptive taint of each fraternity. For instance, if in a fraternity of 10 members there was one actually consumptive member and four "somewhat suspiciously" so, it would count as a fraternity of ten members, of whom two were actually consumptive, and the average taint of the fraternity would be reckoned at one-fifth part of the whole or as 20 per cent.

Treating each fraternity separately in this way, and then averaging the whole of them, the mean taint of the children of one consumptive parent was made out to be 28 per cent.

Distribution of Fraternities.-Next I arranged the fraternities in such way as would show whether, if we reckoned each fraternity as a unit, their respective amounts of consumptive taint were distributed " normally " or not. The results are contained in line A of the following table :

PERCENTAGE OF CASES HAVING VAAIOUS PERCENTAGES OF TAINT.

 
 

Percentages of Taint.

 

0

and

under

9

10

and

under

19

20

and

under

29

30

and

under

39

40

and

above

total,

A. 66 cases, one

parent con-

27

20

9

15

29

100

sumptive.

           

B. 84 cases, one

     

-

   

brother con-

49

14

10

13

14

100

sumptic e.