IV 



ELECTROMOTIVE ACTION IN MUSCLE 



411 



cessively sensitive to a brief duration of current (variations of 

 current), it was natural to apply it to the determination of the 

 current of action in muscle. Hermann (45) was the first to 

 experiment with the telephone, but he failed to detect any 

 action current. Bernstein and Schoenlein (46), on the other_ 

 hand, obtained positive results in 1881 with Siemens' telephone. 

 If 4 to 6 frogs' gastrocnemii were laid in working order upon non- 

 polarisable electrodes (pads), and their nerves simultaneously 

 excited, a " crackling sound " was plainly audible in the telephone, 

 which diminished in clearness with prolonged excitation. Further 



FIG. 13(3. Photographic record of action current in Frog's gastrocnemius in strychnia tetanus. 

 (c, c), curves of contraction. (Delsaux.) 



investigations were carried out on the rabbit. The gastrocnemius 

 muscles were exposed and connected with the telephone by unpolar- 

 isable electrodes, or simple metal needles were pushed through the 

 skin into the muscle, and thence led off to the telephone (Bernstein, 

 47). In both cases audible tones were obtained, provided the 

 sciatic nerve, which had previously been divided, was tetanised. 

 It was found, on exciting with the acoustic current interrupter, 

 that the number of stimuli might reach 700 per sec., when 

 the note in the telephone, corresponding with the interrupter, was 

 heard with musical integrity. Every note sung into a second 

 telephone (exciting telephone to sciatic) was clearly distinguish- 



