Dr. Tómasson's interesting remarks on the therapeutic effect of adrenergic and cholinergic drugs lead me to mention some experiments with benzedrine recently carried out at the Maudsley Hospital. These experiments primarily originated from different considerations. They were part of more extensive investigations into the connection between mental phenomena and blood-pressure and its fluctuations. Benzedrine seemed to be suitable for experimental alterations of the blood-pressure because its effect on arterial tension lies between that of adrenaline and ephedrine with regard to rapidity and intensity of action. Experiments on normal persons demonstrated a peculiar stimulating and euphorizing effect of the drug. The experimental subjects were selected as normal in regard to blood-pressure. They included several cases of mild depression. These also showed either a slight elation, or at least a decrease of their depression after the administration of the drug. This result encouraged further experiments on depressives of various kinds. These were always carried out in the following way: Patients whose mental state was well known and who had been constant for a period with regard to their blood-pressure were given at first small, and later slowly increasing doses of the drug. There were intervals without medication in which the subjects received inert tablets of the same appearance and taste as the benzedrine. The blood-pressure was taken several times daily.