E. SCHTTSTER 
400 
as compared to class 4 ( 0386), while classes 2 and 3 are intermediate between the 
two with '0794 and '0930 respectively. I do not however intend going into this 
point, as it is dealt with by Fay in some detail. I have not made nse of Fay's 
tables principally because no distinction of the sexes was made, fathers and 
mothers were grouped together, and I thought it advisable to keep them separate 
to see whether the paternal correlation was different from the maternal. 
The next step was to tabulate all those cases in which either the father or the 
mother of the husbands and wives of the marriages recorded was deaf. For the 
result of this process see Table II. The total number of husbands and wives in 
TABLE 11. 
Showing the whole number of husbands and wives about ivhom definite infor- 
■ mation is given as to ivhetlier or no they had any deaf relatives other than 
cJiildren and brothers and sisters, also what number of these had either one 
or both varents deaf. 
Congenital 
Adventitious 
Total 
Number 
Father 
Deaf 
Mother 
Deaf 
Both 
Parents 
Deaf 
Total 
Number 
Father 
Deaf 
Mother 
Deaf 
Both 
Parents 
Deaf 
Husbands . . . 
Wives 
648 
672 
11 
12 
7 
13 
37 
36 
1147 
1184 
4 
5 
3 
3 
13 
14 
this table means the total numbers about whom definite information was given as 
to whether or not they had deaf relatives other than children or brothers and 
sisters. The numbers in the columns " Father deaf," " Mother deaf," " Both 
parents deaf," possibly do not represent the whole numbers about whom this 
statement could have been made truthfully ; but they must be looked upon 
as giving minimum values for them. 
It was from Tables I. and II. that the paternal and maternal correlation tables 
were constructed. As it was only possible to divide the material into two classes, 
namely deaf and hearing, the ordinary form of correlation table could not be used, 
and the fourfold method had to be adopted. This method involves an assumption, 
which in the present instance it is impossible to test, that the distribution of the 
material with regard to the variable character dealt with is normal. Where this 
is the case, or even approximately the case, it has been shown that one obtains 
practically the same results from this form of table as one does from the longer 
one. 
The actual process of constructing the correlation table was as follows : 
firstly, from Table I. one learns that 2717 deaf fathers (classing those that were 
born deaf and those that became deaf after birth together) have 464 deaf children 
and 4470 hearing children, also 4-50 children about whom it was not known 
