Dr Bodil Hjorth, who is Assistant Physician to the Keller's Institution in Copenhagen, found that out of 750 imbeciles 30 presented the characters of Mongolian idiocy. The proportion is the same in England and Sweden. In Germany, he tells us, it is from 1 to 2 per cent.

Mongolian idiocy is so marked and specific a form that one might expect it to have a determinate cause. The author has collected information about the parentage and birth of twenty-one Mongolian idiots, which he gives in a statistical table. The observed conditions assumed as possible causes are phthisis in the parents or grandparents, neuropathic heredity, and alcoholism. None of these occur so often as to show a preponderating influence. There is no record of syphilis in any of the cases. Twins, both presenting the specific characters, are noted, the father a day labourer, æt. 41, the mother æt 42. These children were the eighth and ninth of a family of ten. Out of 21 cases, 12 of these Mongolians were the last children in the family.

William W. Ireland