Causation of Mongolism.

EVER since Dr. Langdon Down in 1866 introduced the term " Mongolism," this group of aments has been the subject of numerous investigations. But so far the cause of Mongolism remains obscure and, in spite of a growing amount of literature, it is impossible to say whether there is a single cause for all cases of Mongolism or whether various etiological factors are to be held responsible. Careful investigation of one-hundred and thirteen Mongols-seventy-five males and thirty-eight females-admitted to this Hospital during the last twenty years has enabled me to question the validity of the causes put forward by other observers and to form my own opinion as to the probable cause. Very valuable contributions have dealt with the influence upon Mongolism of heredity-Brushfield, Fantham, Orel; of alcoholism and syphilis-Lind, Riddel, and Stewart; lack ofvitamins and hormonesTredgold; feetal hyperthyroidism-Clark; diminished potency of the secretion of the corpus luteumPenrose; and infusion of racial Mongolian blood into the family-Crookshank. Shortage of space compels me just to refer to these writers and their theories and ideas. I shall now discuss exogenous factors having direct influence upon the pregnant uterus and would subdivide them into:-