Elements of human physiology (1907) Elements of human physiology elementsofhumanp05star Year: 1907 120 PHYSIOLOGY A more convenient form is that devised by Bm'don- Sanderson, in which the glass tube is bent into a U (Fig. 51). The mouth of the tube is closed by a smaller glass tube plugged with clay, and bearing a plug of normal saline clay. If a muscle such as the sartorius be removed from the body, and two non-polarisable electrodes connected with a delicate galvanometer be applied to two points of its surface, there will be a deflection of the mirror attached to the galvanometer, showing t
Elements of human physiology (1907) Elements of human physiology elementsofhumanp05star Year: 1907 120 PHYSIOLOGY A more convenient form is that devised by Bm'don- Sanderson, in which the glass tube is bent into a U (Fig. 51). The mouth of the tube is closed by a smaller glass tube plugged with clay, and bearing a plug of normal saline clay. If a muscle such as the sartorius be removed from the body, and two non-polarisable electrodes connected with a delicate galvanometer be applied to two points of its surface, there will be a deflection of the mirror attached to the galvanometer, showing the presence of a current in the muscle from the ends to the middle, and in the external circuit from the middle (or equator) to the ends. It was formerly thought that this current was always present in all normal muscles, and it was spoken of as the ' natural muscle Fig. 50. S-yinw- a. C. Fig. 51. Fig. 50.—Diagram of non-polarisable electrode, a. Covered wire. h. Amalgamated zinc rod. c. Glass tube. d. Saturated ZnSO solu- tion, e. Plug of zinc sulphate clay. /. Plug of normal saline clay. Fig. 51.—U-shaped non-polarisable electrodes. current;' the muscle was said to be made up of a series of electromotive molecules, the equator of each molecule being positive to the two poles (Du Bois Eeymond). It has been conclusively shown however (by Hermann and others) that this current of resting muscle is not a natural current at all, but is due to the effects of injury in making the pre- paration. The less the preparation is injured, the smaller is the current to be obtained from it, and in some contractile tissues, such as the heart, there may be absolutely no current during quiescence. Hermann describes the fact of the existence of currents of rest thus :—' In partially injured muscles every point of the injured part is negative towards the points of the uninjured
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