Indirect, or extra-muscular electrization, next claims our attention. You will recollect that it is produced by acting upon the special nerve trunk and its branches, instead of by placing the rheophores upon the muscle itself. We may thus call a motor nerve into action without affecting the cutaneous nerves, and with a minimum of power of current, and necessarily a minimum of sensation which hardly ever need amount to actual pain. This method is preferable, therefore, in cases where we desire to produce muscular contraction and as little sensation as may be, and again when the sedative influence of the constant Voltaic current is required to be localized in any special nerve. In its application it is convenient to place a good-sized sponge connected with one pole upon an indifferent part of the body, such as the sternum, and to apply a pointed conductor from the second pole directly over the course of the nerve it is desired to act upon. Speaking generally, these motor points as they are called may be selected by reference to a good anatomical plate, but only approximately, for we know that it is common to find variations in the course of the nerves and in the mode of their distribution among the muscles, and this being so, it is well when we propose to act upon a motor or mixed nerve (which is not paralyzed), to make sure that we are localizing the current in it by producing for a moment the contraction of its muscles and then marking the spot by touching it with a pencil of nitrate of silver. This, of course, is only necessary where in our subsequent electrization we do not wish muscular contraction, as in the treatment of neuralgia.[12] I will demonstrate indirect electrization by Faradizing the median nerve in my left forearm above the wrist, and before it passes beneath the annular ligament of the carpus. It lies a little below the surface, between the tendons of the flexor carpi radialis and palmaris longus. You observe that its muscles powerfully contract and oppose the thumb to the other fingers, at the same time abducting it. There occurs also a slight flexure of the first phalanges of the index and middle fingers. Professor Ziemssen in his work on Medical Electricity has published some extremely accurate plates of the motor points of the body, and I have grouped together the more important of them in a chart or map for convenient reference.[13] Ziemssen’s method of procedure was to find out experimentally the points where the application of electricity most readily produced muscular contraction. He then marked these points with coloured chalk, and after a sufficient number of trials with nitrate of silver. Photographs of the parts thus marked were taken and afterwards transferred to the wood blocks. These figures may therefore claim to be true to Nature, although they may not be absolutely correct for every individual. Ziemssen verified their approximate exactitude by following