marriage the wife became insane and two of the children were idiotic.  In a case of the marriage of cousins, themselves the offspring of cousins the husband was a hypochondriac, and seven children idiotic.  In another marriage of the same class both parents were feeble-minded and the children idiotic.  These are simply taken at random, and many others might be given.  When we find also that in a majority of cases no report is given of the ancestry, it is very obvious that consanguinity alone could not have been the cause of any large proportion of the 308 cases of idiocy in the Bemiss report.

[Footnote 70:  Barr, op. cit., p. iii.]

[Footnote 71:  Bemiss, op. cit., p. 420.]

My own investigations show that out of 600 children of first cousin marriage (from correspondence) 26 or 4.3 per cent are mentally defective—­10 are reported as “idiots,” 13 as “weak-minded” and 3 as “imbeciles.”  In at least five of these cases there is evidence of bad heredity, in two others the father was intemperate and in two more causes acting after birth are mentioned.

The statistics of the insane and idiotic in Prussia presented by Mayet clearly indicate the large part which heredity plays in the production of mental disorders.  Tables XX and XXI set forth the most important results of his work.  Mayet considers a case hereditary if any near relative of the subject suffered from mental or nervous disorder, or was intemperate, suicidal, criminal or eccentric.[72]

[Footnote 72:  Mayet, Verwandtenehe and Statistik, quoted by Feer, Der Einfluss der Blutsverwandschaft der Eltern auf die Kinder, p. 13.]

TABLE XX.
--------------------------------------------------
| No. of |Percentage
| Cases. |hereditary.
--------------------------------------------------
1.  Simple Insanity          |102,097 | 31.7 = 100
Consanguineous parentage |    664 | 69.0 = 218
Parents cousins          |    595 | 68.1 = 215
Parents uncle and niece  |     66 | 77.3 = 244
--------------------------------------------------
2.  Paralytic Insanity       | 22,936 | 17.6 = 100
Consanguineous parentage |     95 | 45.3 = 257
Parents cousins          |     87 | 44.8 = 255
Parents uncle and niece  |      8 | 75.0 = 426
--------------------------------------------------
3.  Epileptic Insanity       | 14,067 | 25.6 = 100
Consanguineous parentage |     79 | 53.2 = 208
Parents cousins          |     70 | 50.0 = 195
Parents uncle and niece  |      9 | 66.7 = 261
--------------------------------------------------
4.  Imbecility and Idiocy    | 16,416 | 28.7 = 100
Consanguineous parentage |    237 | 43.0 = 150
Parents cousins          |    211 | 43.1 = 150
Parents uncle and niece  |     26 | 38.5 = 134
--------------------------------------------------

Table XXI gives the proportion of the mentally defective who are the offspring of consanguineous marriages.  The term “cousin” in both these tables probably means first cousins.  It will be remembered that Prussian statistics of consanguineous marriages are very imperfect, but that at least 6.5 in every thousand are consanguineous (first cousins or nearer).