In the field of psychiatry, alienists are practically agreed as to the predisposing causes of insanity, but when the exciting or immediate causes are considered a wide diversity of opinion is found. The generally accepted theory is that the exciting cause has a physical basis; and this view has been greatly strengthened by the writings of Kraepelin and the researches of Bruce, Morro, Blin and others. Too much evidence has been produced in favor of the theory of autointoxication and a toxemia to be rejected without investigation. That the condition known among American authorities as primary dementia, and by the Germans and French as dementia præcox, is the result of a toxemia, seems to be fairly well established. That acute and agitated melancholia and mania are caused by profound changes in the metabolism of the body by some toxic agent, an examination of the blood changes seems to justify. As