Reotom

REOTOM, an apparatus used in electrophysiology for the study of action currents in living tissues. The reotom proposed by Bernstein for this purpose consists of a disk that rotates freely around a vertical axis, equipped with two pins on its periphery. One of these pins, fixed immovably on the disk, by closing and opening the current in the primary coil of an induction apparatus, causes irritation of the object; the second, movable pin, is for connecting the action current coming from the object to a galvanometer. When the disk rotates at a known speed, the preparation is irritated with each revolution and communication with the galvanometer is established for a known time. If the contacts are arranged so that the galvanometer closes at the same moment as the closing and opening of the induction coil, the galvanometer deflection will correspond to the initial stage of the action current; however, if the second pin, which serves to divert the current to the galvanometer, is moved back so that it lags slightly behind the first during disk rotation, the diversion of the action current to the galvanometer will occur later than the irritation of the object. Through a series of successive shifts of the second pin, various phases of the action current arising in the tissue can be diverted to the galvanometer, and thus a complete picture of its progression in the tissue from beginning to end can be constructed. With the introduction of Einthoven's galvanometer into physiological methodology, Bernstein's reotom at present represents only historical interest.