ELECTRICAL CHANGES IN TISSUES 



649 



refer to the total concentration of all the diffusible ions of the same sign present, 

 since interchange takes place freely at the contact surface. Thus the chemical 

 nature of the ion does not appear to enter into consideration. 



B 



03- 



02- 



SEC. -01 



FIG. 205. DIPHASIC ELECTRICAL CHANGE IN UNINJURED SARTORIUS MUSCLE. 



A, Photograph of excursion of capillary electrometer. First with a single stimulus. Then, a second time, 



with an additional stimulus at 0'022 sec. later. The change due to the latter is fainter, because only 

 recorded once. Time in 200 per second. 



B, Similar photograph with another additional stimulus at O'OIO sec. after the first, and between it and the 



second. 



In addition to the form of the diphasic response, as recorded by the capillary electrometer, these two 

 figures show that a stimulus, occurring in the refractory period due to a previous one, has no effect on the 

 result of a stimulus given just at the beginning of the return of excitability. That is, a stimulus in the 

 refractory period does not set up any further refractory state. 



(Keith Lucas, Jl. Physiol., 43, p. 52.) 



C, Analysis of a capillary electrometer record of a diphasic response of the gastrocnemius muscle to a single 



stimulus applied to the sciatic nerve. Muscle led off from the middle and the tendinous end. 



(Keith Lucas, Jl. Physio!., 41, p. 371.) 



