------
[A] See Table XXV.

In Scotland Dr. Arthur Mitchell made inquiry of the superintendents of
a number of deaf-mute asylums, and found that of 544 deaf-mutes, 28
were the offspring of 24 consanguineous marriages.[85] There were 504
families represented in all, so that the average per family was 1.17
among the consanguineous to 1.07 among the non-consanguineous.

[Footnote 85: Huth, op. cit., p. 226.]

In Norway, according to Uchermann, while 6.9 per cent of all marriages
are consanguineous within and including the degree of second cousins,
and in single cantons the percentages range as high as 31.0, only in
one single district does the number of the deaf-mutes harmonize with
that of the marriage of cousins. The district of Saeterdalen has the
greatest number of consanguineous marriages (201 out of 1250), but not
a single case of deaf-mutism. Hedemarken, which has the fewest
consanguineous marriages has a great many deaf-mutes. Where
deaf-mutism exists it seems to be intensified by consanguinity, but
where it is not hereditary it is not caused by consanguinity. Of the
1841 deaf-mutes in Norway, 919 were congenitally deaf, and of these
212 or 23 per cent were of consanguineous parentage.[86]

[Footnote 86: _Les Sourds-muets en Norvege_. Quoted by Feer, _Der
Einfluss der Blutsverwandschaft der Eltern auf die Kinder_, p. 22.]

Dr. Feer gives a table containing the results of a number of studies
of deaf-mutism, which shows an average of 20 per cent as of
consanguineous origin. Four investigations give the number of children
to a family. Table XXVII from Feer seems to indicate that the Irish
census is fairly accurate at this point.[87]

[Footnote 87: Feer, op. cit., p. 22.]

TABLE XXVII.
_Average Number of Children to a Family._
-------------------------------------------------
|Consanguineous|"Crossed"
Observer. | marriages. |marriages.
-------------------------------------------------
Huth (Irish Census) | 1.68 | 1.17
Wilhelmi | 1.71 | 1.26
Mygind | 1.53 | 1.20
Uchermann | 1.41 | 1.19
-------------------------------------------------

In the American Census the instructions to enumerators have been so
diverse that statistics of the deaf have been very poor until recent
years. Not until the Twelfth Census was the inquiry put upon a really
scientific basis.

This reform, as also the more inte