THE MUSCULAR CURRENT. 293 



pool, I chose twenty, which I put into water that had boiled for two hours. I covered 

 the glass cylinder in which this water was contained, with a plate of glass which I 

 luted to the cylinder. To prevent the water from again taking up air, I covered the 

 surface with oil. The temperature of the water was +15° C. The frogs appeared 

 more vivacious at the commencement of the experiment, from their continual move- 

 ment from the surface of the water to the bottom, and vice versd, but it was not 

 long before this vivacity ceased, and in about an hour they were all at the bottom 

 of the cylinder, showing signs of suffering, and with but little motion. In two hours 

 all motion entirely ceased and the frogs seemed dead. I have repeated this experi- 

 ment twice with the same result, the only difference discoverable was in the time, 

 which varies inversely as the temperature of the medium. The signs of the muscular 

 current are considerably weakened in a pile composed from frogs which have been 

 labouring under asphyxia for some time. Thus, while a pile composed of frogs which 

 had not been submitted to any previous injury, caused a first deflection of 90°, and 

 the needle remained fixed between 25° and 30°, with a pile equally composed of 

 twenty elements, but which had been taken from frogs in a state of asphyxia, the 

 first deflection was not more than from 50° to 60°, and the needle stopped at from 

 10° to 12°. This difference is very striking, and the influence of a normal state 

 of the sanguineous circulation and respiration could not be more clearly demon- 

 strated. I will mention here a singular appearance of the muscles in frogs as- 

 phyxiated : the muscles are almost white, and acquire a slightly red tint from 

 exposure to the air. I was desirous to renew and verify the singular action of 

 sulphuretted hydrogen. The following numbers, the result of various experiments, 

 show that the muscular current is very much weakened in frogs killed by this gas. 

 Twenty elements, or half thighs of frogs killed in the usual manner, gave a deflec- 

 tion of 56°. Another twenty elements taken from the same mass gave 44°, another 

 similar pile 41°. 



I will now sum up the results obtained from these different experiments. In the 

 first place, the intensity and duration of the muscular current are independent of the 

 nature of the gas which envelopes the muscular pile. Secondly, this current, as I have 

 already shown from the commencement of my researches, is altogether independent 

 of the cerebro-spinal nervous system, and the circumstances which exercise a marked 

 influence upon its intensity are respiration and the sanguineous circulation. Thirdly, 

 those poisons which seem to act directly upon the nervous system, have no influence 

 upon the muscular current ; among these I would mention hydrocyanic acid, mor- 

 phine and strychnine. Fourthly, sulphuretted hydrogen has a marked influence in 

 diminishing the intensity of the muscular current. Fifthly, the intensity of the mus- 

 cular current varies according to the temperature in which the frogs have lived a 

 certain time ; it is needless to observe that this result is not discoverable except in 

 those animals which like the frog necessarily take their temperature from that 

 of the medium in which they live. Sixthly, the intensity of the muscular current 



2 Q 2 



