While working with psychotic patients in a study of sodium cyanide as a respiratory stimulant, Loevenhart and Lorenz and their co-workers1 found evidence of greater cerebration in stuporous patients. They repeated their work,2 using high percentages of carbon dioxide, and found in stuporous patients, with conditions variously categorized as dementia praecox, manic-depressive psychoses or involutional melancholia, but alike in their relative mutism and noncommunicativeness, a definite, certain and invariable response. Their method of procedure was to use an ordinary nitrous oxide anesthetic machine, and by means of this to regulate the relative percentage of gas as follows: Starting with 10 or 15 per cent of carbon dioxide and the remainder oxygen, they gave this mixture for one minute and then each minute thereafter increased the amount of carbon dioxide at the rate of 5 per cent a minute until between 30 and 40 per cent of carbon dioxide