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Mr. Fay concludes that the married deaf have married deaf rather than hearing partners, chiefly from the sympathy engendered by their condition and only secondarily because of opportunities for acquaintance afforded by the schools for the deaf. On the whole, the marriages of these persons are slightly less productive than ordinary marriages, but their offspring are much more liable to be deaf than those of ordinary marriages in the proportion of 8.6 to .01 per cent.

The table shows that congenitally deaf persons, whether they are married to one another, to adventitiously deaf, or to hearing partners, are far more liable to have deaf offspring than adventitiously deaf persons, the percentage of deaf children of the one ranging from 6 to 25 per cent, in the other from 2.3 to 4.3 per cent. Deaf persons having deaf relatives, however they are married, and hearing persons having deaf relatives and married to deaf partners, are very liable to have deaf offspring. The marriages of the deaf most liable to result in deaf offspring are those in which the partners are related by consanguinity. The extremes of liability are found in the two classes last named in the table, i.e. both partners adventitiously deaf without deaf relatives having .3 per cent deaf children, while the consanguineous partners had 30 per cent deaf children. (81)

Dr. Strahan regards congenital deafness as a sign of general decay, which, if deepened by intermarriage, must extinguish the family; (82) and he names as transmissible by inheritance -- and as at once results, evidences, and causes of degeneration -- a list of diseases such as insanity, imbecility, epilepsy, drunkenness, deaf-mutism, blindness, cancer, scrofula, tuberculosis, gout, rheumatism, and instinctive criminality. While his facts do not support all of his contentions, they show the interdependence of many of these diseases. The evidence of other medical men as to the transmissibility of certain neurotic tendencies is unanimous. Dr. Samuel G. Howe, in 1848, collected information showing not only the hereditary tendency to idiocy in certain families, but also the interchangeability of this and other forms of degeneration.

TABLE XVIII.
Idiocy in Massachusetts.
Condensed from Howe's Report, 1848.

Table XIX., condensed from Dr. Barr's recent work, shows these same facts more conclusively.

TABLE XIX. -- CAUSES OF FEEBLE-MINDEDNESS. (83)

This table shows that from 40 to 65 per cent of all feeble-mindedness is due to hereditary neuroses, from 8 to 14 per cent to abnormal conditions of the mother during gestation -- a total of 55 to 71 per cent due to prenatal influences. Dr. Barr explains that the divergence in the English and American cases between the percentage attributed to hereditary causes and abnormal condition of the mother is more apparent than real. On this point he says: --