E. Schuster 
475 
TABLE XII. 
Comparing distribution of size of families luhich contain at least one congenitalhj 
deaf person, tuith that of those containing at least one person said to have 
acquired deafness. 
Nature of Deafness 
Number 
in 
Totals 
Family 
Congenital 
Acquired 
Doubtful 
1 
32 
73 
6 
111 
'2 
83 
218 
18 
317 
S 
lift 
OO / 
1 7 
466 
h 
180 
365 
16 
550 
,5 
168 
344 
17 
518 
G 
144 
323 
18 
476 
117 
260 
16 
383 
8 
97 
215 
12 
316 
!J 
OO 
1 / D 
1 1 
i i 
262 
10 
58 
103 
8 
163 
21 
46 
55 
5 
13 
31 
50 
1 
81 
IJ 
18 
35 
49 
u 
5 
11 
14 
15 
5 
6 
11 
16 
1 
5 
1 
/ 
17 
1 
3 
4 
18 
1 
1 
10 
I 
1 
20 
1 
1 
21 
1 
1 
22 
23 
1 
1 
Totals 
1193 
2583 
146 • 
3837 
N.B. 85 families arc included both in the congenital and iu the acquired class, as they 
contain at least one member of each of these two classes. 
concrete example of this; consider a family of 12 persons containing 6 deaf 
members and 6 hearing. Taking the deaf members first each of them can be 
paired with each of the other deaf ones, thus making 30 pairs of deaf and deaf; 
they can also be paired with the hearing members, making 36 pairs of deaf and 
hearing ; similarly the 6 hearing persons can be paired with the G deaf, making 
36 pairs of hearing and deaf, and with one another, making 30 pairs of hearing 
and hearing. The results can be written in tabular form as in Table XIII. Out 
of a family of 12, 132 pairs can be made, and, speaking generally, out of a family 
of n members n{ii-\) pairs can be made. Table XIV. is the sum of tables such 
as XIII. made for each family. 
Now there are altogether 5423 deaf persons in the families used, and the 
distinctive point of these families is that they contain at least one married deaf 
