THE MUSCULAR CURRENT. 287 



which was continuously formed. I then closed the circuit, and the deflection at first 

 was 85°; as usual the needle oscillated, retrograded, and began to be stationary 

 towards 30°. The following numbers show the degree of deflection at intervals of 

 ten minutes, care having been taken to maintain constantly the degree of rarefaction 

 'unaltered. After the first ten minutes the deviation was 15°, 10°, 7°, 5°, 5°, 4°, after 

 two hours the deflection was fully 3°. On admitting the air into the receiver the 

 needle advanced two or three degrees, then again returned to its deflection of 3°. 

 This slight increase in the strength of the current occurs, as we shall presently see, 

 whatever be the gas introduced into the receiver ; it is also caused by working the 

 air-pump while the circuit is closed, and this is probably owing to the liquid con- 

 tained in the cavities of the pile being put in motion, so that the wires are more or 

 less immersed. The lesser deviation obtained in this third experiment on first closing 

 the circuit was very probably owing to the frog having been killed rather longer than 

 the others, to the muscular elements immediately beginning to dry in rarefied air, 

 and to some bubbles of air which adhere to the platinum wires when the pump is 

 worked. 



I next killed forty other frogs, and with them I composed two piles consisting of 

 twenty elements each pile. I tried the effect of each of these piles separately in con- 

 tact with the air; in one of them the first deflection was 85°, in the other 88°. I 

 then put one of these piles under the receiver and exhausted the air ; I closed the 

 circuit, and the deflection was 81°. The needle oscillated, retrograded as usual, and 

 remained fixed at 15° at the expiration of ten minutes. I now introduced a sufficient 

 quantity of oxygen gas to fill the receiver. The needle oscillated slightly on admit- 

 ting the gas, then contintted retrograding, and after a lapse of thirty minutes it 

 marked 8°, and at the end of another half-hour it showed 4°. 



After this I placed the other pile under the receiver, exhausted the air, and closed 

 the circuit. The first deviation of the needle was 65°. This difference is naturally 

 owing to the length of time the frogs had been killed, that is, all the time taken up 

 by my first experiment. Leaving the circuit closed, the needle as usual continued to 

 retrograde, becoming stationary at 4°, as did the other pile immersed in oxygen. 

 Finally, I re-admitted the air, and the deflection was not increased. 



These experiments are sufficient to show that the muscular current neither varies 

 in intensity nor in duration, after the death of the animal, from keeping the muscles 

 from which it is obtained either in oxygen or in air reduced to a pressure equivalent 

 to one inch of mercury. 



I will now describe the results obtained from operating in the manner above de- 

 scribed, in hydrogen gas. The singularity which this gas offbrs could not certainly 

 have been anticipated before the experiment. 



As usual I prepared a pile of twenty elements, half thighs of frogs ; I placed it 

 under the receiver, and previous to exhausting the air I completed the circle, and the 

 deflection was 85° : the circuit was left closed. I then rapidly exhausted the air 



