In the _American Journal of the Medical Sciences_ for September, 1915, Barton asserts that all the irregularities of the heart-beat which are brought about by digitalis tend to be removed by caffeine. Although in many cases digitalis arrhythmia will spontaneously disappear when the drug is stopped, instances arise, unfortunately too common, in which after prolonged digitalis administration the conductive system is so depressed that serious results may arise. Under these circumstances the administration of caffeine will be of service and is therefore strongly indicated. The action appears to be due to the increase in irritability of the conduction system produced by the caffeine, which antagonizes and finally overcomes the depressing effects which digitalis exerts upon the auriculo-ventricular bundle.—_The Therapeutic Gazette._ THE EFFECT OF CAFFEINE UPON THE BLOOD-FLOW IN NORMAL HUMAN SUBJECTS. The _Journal of Pharmacology and Experimental Therapeutics_, for November, 1915, contains a report of a research by Means and Newburgh in which they report experiments upon the blood-flow of two normal subjects during rest, and of one subject during muscular work. The action of caffeine on the blood-flow was studied in both subjects while at rest, and in one during work. The average blood-flow of the two subjects at rest was 4.5 and 4.0 liters per minute; the systolic outputs were 61 and 57 cc.; the coefficients of utilization of the oxygen-carrying capacity of the blood were 31 per cent and 41 per cent. With increasing work a steady rise in blood-flow, oxygen absorption, and pulmonary ventilation was found. The increase in blood-flow was produced first by an increase in systolic output until a maximum of 118 cc. was reached, beyond that by an increase in pulse-rate. This suggested that the supply of venous blood in this subject becomes “adequate” at about 640 kg. meters of work per minute. The coefficient of utilization showed a slight rise during work, indicating a slightly greater economy of the circulation. After giving caffeine during rest, or when the supply of venous blood is “inadequate,” evidence of drug action was found with both subjects. This action consisted in an increase in total blood-flow without a corresponding increase in oxygen absorption, and hence a decreased coefficient of utilization of the oxygen-carrying capacity of the blood. The pulse-rate was unchanged. Consequently the systolic output was increased. During work probably no other action was obtained from caffeine than possibly an increase in pulse-rate, and consequently slight diminution in systolic output. It is suggested that during rest when the supply of blood to the right heart is “inadequate”, caffeine increases the blood-flow by increasing the venous supply through an action upon some mechanism outside the heart. When the supply becomes “adequate” or approaches adequacy, no such action is obtained.—_The Therapeutic Gazette._