ficulty discover the influence of heredity. In the
congenitally deaf the trace of a physical defect is even more clearly
indicated. Of these 40.1 per cent have deaf brothers, sisters or
ancestors, and 46.2 per cent have also deaf uncles, cousins, etc.[48]

It is thus evident that there are certain families in society deeply
tinged with deafness, that it sometimes passes from parent to child,
from generation to generation, and that like a cloud it hangs over a
section of the race.

THE OFFSPRING OF DEAF PARENTS

All this argument leads up to one most pertinent question: Are the
statistics which we have indicative that this deafness which passes so
remorselessly in certain families will be found all the stronger in the
children of deaf parents? Have we ground to believe or fear that this
deafness will crop out far more surely than in the children of parents
not deaf? And can we determine to what extent possibilities are
increased of the offspring of deaf parents being likewise deaf?

Let us now consider the statistics which we have in this matter, first
examining the results of the census investigation.[49] Of the 8,022
married deaf persons for whom statements are made, we find that there
are 190 who have deaf offspring, or 2.4 per cent. Of the 4,116 deaf
persons who are married to deaf persons, 137 have deaf children, or 3.3
per cent; and of the 3,906 deaf persons married to hearing persons, 53
have deaf children, or 1.4 per cent. Of the married deaf having deaf
children, 52.5 per cent have deaf relatives of some kind, and 54.7 per
cent are congenitally deaf, the proportion of those having deaf
relatives who are also congenitally deaf being 66.7 per cent. Of the
deaf married to hearing partners, who have deaf children, 26.4 per cent
are congenitally deaf, while 50.9 per cent of the partners in such
marriages have deaf relatives of some kind.

From the census statistics, then, it appears that the married deaf as a
class do not have a large proportion of deaf children, and that this
proportion is only a little more than twice as great when the deaf are
married to the deaf as when they are married to the hearing. It appears
also, however, that when there are deaf relatives involved in either
kind of marriages, or when there is congenital deafness in the deaf
parent, the effect is quite marked in the offspring.

Besides the census returns, we have the statistics presented in the
reports of certain schools, which are