the nasal mucosa has been rendered anemic by adrenin pledgets. Von den Velden’s claim[96] for adrenin given by mouth was subjected to a single test on man by Dale and Laidlaw,[97] but their result was completely negative. The importance of Vosburgh and Richards’ observation, the thoroughly discordant testimony of later investigators, as well as the meager and incidental nature of all the evidence that has been adduced either for or against the acceleration of clotting by adrenin, made desirable a further study of this matter. Especially was this further study desirable because of the discharge of adrenin into the blood in pain and emotional excitement. Accordingly, in 1914, H. Gray and I[98] undertook an investigation of the question. In doing so we employed cats as subjects. Usually they were quickly decerebrated under ether, and then continuance of the drug became unnecessary. Body temperature was maintained by means of an electric heating pad. Respiration proceeded normally except in a few instances (in which, presumably, there was hemorrhage into the medulla), when artificial respiration had to be given. The Graphic Method of Measuring the Coagulation Time In order to avoid, so far as possible, the personal element in determining when the blood was clotted, the blood was made to record its own clotting. The instrument by means of which this was done was the graphic coagulometer devised by W. L. Mendenhall and myself,[99] and illustrated diagrammatically in Fig. 24. It consists essentially of a light aluminum lever with the long arm nearly counterpoised by a weight _W_. The long arm is prevented from falling by a support _S_, and is prevented from rising by a horizontal right-angled rod reaching over the lever at _R¹_ and fixed into the block _B_ which turns on the axis _A_. Into the same block is fixed the vertical rod _R²_. When this rod is moved from the post _P¹_, against which it is held by the weight of the horizontal rod _R¹_, towards the other post _P²_, the check on the long arm of the lever is lifted, and if the short arm is heavier, the long arm will then rise. [Illustration: Figure 24.--Diagram of the graphic coagulometer. The cannula at the right rests in a water bath not shown in this diagram. For further description see text.] The cannula _C_, into which the blood is received, is two centimeters in total length and slightly more than two millimeters in internal diameter. It is attached by a short piece of rubber tubing to the tapered glass tube _T_, five centimeters long and five millimeters in internal diameter. The upper end of this tube is surrounded by another piece of rubber which supports the tube when it is slid into the U-shaped support _U_, fixed directly below the end of the short arm of the lever.