is being the case, it is no
longer possible for children in the public schools to continue their
studies when suffering from diseased tonsils and enlarged adenoid
vegetations. From this cause alone, many cases of impairment of hearing
which usually occur later in life will be prevented in the future". By
Dr. E. A. Crockett, of Harvard University, it is believed that, although
there is a larger amount of deafness from measles, there is less, not
only from scarlet fever, but also from chronic suppurations, from
adenoid and throat troubles in general, and even from meningitis, owing
to the use of serums. Regarding his own observations, within a period of
twenty-five years "the number of extremely deaf persons and deaf-mutes
has very materially diminished".

[41] Hereditary deafness is sometimes of a kind that manifests itself
some years after birth, often with certain relatives similarly affected.
This is especially true of catarrhal and middle ear affections, though
their results may more often be partial rather than total deafness.

[42] In a part of such deafness, and also in a portion of that occurring
shortly after birth, the cause is said to be syphilis. See Proceedings
of International Otological Congress, ix., 1913, p. 49; _Volta Review_,
xiv., 1912, p. 348; xv., 1913, p. 209.

[43] Special Reports, pp. 125, 236. There were 3,341 who failed to
answer, and if all had made reply, our percentage would probably be
higher yet.

[44] P. 108.

[45] In the Louisiana School 10 per cent of the pupils are said to have
parents who were blood relatives; in the Illinois, 5 per cent; and in
the Kansas, from 5 to 5.5 per cent. Report of Louisiana School, 1906, p.
17. See also Transactions of American Medical Association, xi., 1858,
pp. 321-425; Proceedings of Conference of Principals, iii., 1876, p.
204; _Annals_, xxii., 1877, p. 242.

[46] On this subject, see Francis Galton. "Natural Inheritance", 1889,
p. 132ff. See also G. B. L. Arner, "Consanguineous Marriages", 1908, p.
65ff.; C. B. Davenport, "Heredity in Relation to Eugenics", 1911, p.
124ff.

[47] Special Reports, pp. 128, 235, and _passim_.

[48] These proportions are further indicated in the succeeding section.

[49] Special Reports, p. 135ff.

[50] Report, 1908, p. 31.

[51] Out of 107 children born to former pupils of the Minnesota School
up to 1892, 2, or 1.9 per cent, were deaf. Report, 1892, p. 39. Out of
811 children born to former pupils of the Amer