Professor Bartholow, in his treatise on Medical Electricity says: “As animal tissues are composed of substances amenable to electrolytic decomposition, it is obvious that they must yield up their component elements in accordance with the laws of electrolysis. Albumen is coagulated, salts are separated into acids and bases, and water is resolved into oxygen and hydrogen. When the salts contained in the animal tissues—soda, potassa, lime—and water, are decomposed, the acids and oxygen appear at the positive pole, and the alkalies and hydrogen at the negative. It follows that if the positive electrode be composed of metal, it will be corroded by the action of chlorine and the acids, and the negative will remain unacted on and smooth. The tissues in the vicinity of each electrode are necessarily affected by the elements brought to them in accordance with chemical laws. About the positive the mineral acids and chlorine form combinations, and hence do not attack the tissues with the same energy as those about the negative pole. If, however, the positive electrode is composed of zinc, for example, the chlorine attacking it will form chloride of zinc, a very corrosive material. This principle has been utilized to produce caustic effects at the positive pole. Although the negative electrode remains smooth, much more than at the positive are seen these destructive effects from the action of the free alkali liberated in its neighborhood. When an ordinary electrode of carbon covered with soft sponge is made to conduct a strong galvanic current, the skin speedily becomes reddened, and may be made to ulcerate if the contact is sufficiently prolonged. If the carbon is applied directly, an intense burning is produced and the tissues are destroyed, leaving a slough, which is slowly detached and the ulcer remaining is difficult to heal. The caustic action is due chiefly to the soda, potash, and lime. Some effect must also be allowed to the disassociation of the tissues, to their transference from point to point and at the negative pole to the mechanical action of the liberated hydrogen.” Interpolar regions. The reader must have been impressed with the peculiarity of each pole in possessing affinity or attraction for certain elements that constitute the animal tissue. Oxygen and acids accumulate around the positive pole, while alkalies are attracted to the negative pole; thus it must be an absolute fact that an actual transfer of particles in both directions to each pole must traverse the tissue lying between the two poles; this accounts in a great measure for the difference of the local effect on the tissues around the poles, one being in the nature of an acid the other of a caustic alkali. This naturally gave rise to an inquiry as to the effect that the galvanic current has on the structure between the two poles.