SINCE Sir Charles Scudamore [1824] studied the effect of an electric current on the blood, only two papers have appeared on this subject. Stern [1916] made an experimental study on the influence of current on blood coagulation; Leiri [1934] made an interesting study from a purely theoretical viewpoint, without reporting any experiments. Stern used the method of Cannon & Mendenhall [1914] to register the coagulation time of blood. In this method the movemiients were recorded of a wire loop which just fitted into a very narrow tube filled with blood; Stern use(c this wire as the positive pole. His claims of a reduction of the coagulation time of blood due to current flow were found in the experiiients described below not to be quite correct. Since with this technique only occurrences on, or very near to, the positive pole could be observed, his claiims hold good only for the imimediate surroundings of this pole. AWhat happened in the bulk of the blood and on the negative pole escaped observation.Neither Scudamore nor Stern used electrodes of chemically inert metals, such as platinum, etc. They did not investigate whether their results were due to what might be called non-specific coagulationi of soilie proteins by the current, or to a true influence on the physiological process of blood coagulation. It was the purpose of the experinments described below to get some information on these lines, and a method was designed which allowed a rough quantitative comparison of the action of different electrodes and at the sam-ie time permitted distinction between what happened on the charged surfaces and in the bulk of the blood.