152 STUDIES IN ELECTRO-PHYSIOLOGY: 



B depicts the sarcomere in contracted condition, 

 compressed and elongated and bulging at the sides. 



The analogy between 

 metallic plates and the 

 " clear " spaces, b, of the 

 sarcomere cannot, of 

 course, apply to the 

 Fig * 82 * material employed, but 



only to its electrical character. I am informed that 

 the " clear " spaces are largely composed of potassium 

 salts in fluid or semi-fluid form, and that the dark 

 vertical lines are canals or pores, open towards Krause's 

 membrane, but closed at Hensen's line. The clear 

 spaces are therefore conductive, and the analogy, elecitri- 

 cally, holds good. In the contracted muscle the clear 

 part of the muscle substance passes into the canals or 

 pores and disappears from view, swelling up and widening 

 the sarcous element and shortening the sarcomere. In the 

 extended muscle, on the other hand, the clear substance 

 passes out from the canals of the sarcous element and lies 

 between it and the membrane of Krause, again ready 

 for action. 



The effect of the completed contraction is to cause the 

 conducting plates to approach each other near enough to 

 enable them to discharge or neutralise their charge by 

 contact through some invisible pore in Hensen's line ; or, 

 possibly, by osmosis or diffusion. 



Alternatively such action may be made to occur by 

 the plates being withdrawn to a sufficient distance to cause 

 induction to cease. Then, the impulse having pa'ssed, 

 they would be restored to their former position, in readiness 

 to resume the performance of their function. 



In this connection we may recall the " Muscle telegraph " 

 of Du Bois-Reymond. He attached a piece of muscle to 

 a movable disc and placed the former in the circuit of a 



