THE MUSCULAR CURRENT. 291 



Pour frogs exposed to a temperature varying from 0° to 4°, produced in twenty- 

 four hours 0-5 cubic centimeters of carbonic acid ; four other frogs placed in the 

 same recipient and in the same conditions, but at +16° C, gave 0-3 cubic centimeters 

 of carbonic acid. The celebrated experiments of Edwards give double this number 

 at a temperature of +27° C. We now come to the signs of the muscular current. 

 In the coldest days of the past winter twenty elements gave a deflection of 32°, then 

 in succession, as the temperature of the air increased, 38°, 48°, 50°, 56°, 60°, 66°. 

 These indications correspond to the gradual increase of the temperature from 0° to 8°. 

 Finally, in the present month, the thermometer rising to +15° in the shade, the inten- 

 sity of the muscular current was expressed by the numbers 80°, 85°, 90°. It is need- 

 less for me to repeat that these numbers refer to the first deviation which takes place 

 on closing the circuit of the pile of twenty half thighs of frogs, always disposed in 

 the same manner, and with their extremities immersed in the two cavities of the 

 board, filled with spring water. 



I attained to the same result, comparing the intensity of the muscular current 

 produced by frogs recently caught in the cold season, with that obtained from 

 frogs which had been left for the space of twenty-four hours to forty-eight hours 

 exposed to a temperature of +16°C. The following are some of the many num- 

 bers noted down, for the sake of demonstrating, even in this case, the relation be- 

 tween the intensity of the muscular current and the temperature in which the frogs 

 have lived. A pile composed of frogs caught in the coldest part of the season 

 have produced a deflection of 32°. The deflection caused by other similar frogs 

 which were kept for two days in a warmer temperature, was 38°. In another case 

 the muscular current rose from 30° to 48°, in another from 50° to 64°, in another 

 from 66° to 85°. 



I would observe, however, that if the frogs are kept too long exposed to a warm 

 temperature, and deprived of the medium in which they generally live and are nou- 

 rished, instead of the increase of the muscular current, produced by an increase of 

 temperature taking place, a considerable diminution of the current follows in com- 

 parison with that of the frogs recently caught. Experience has also shown me (that 

 which was easy to foresee), that in proportion to the elevation of the temperature in 

 the frogs originally, so much the sooner the effiict of the want of nutrition was 

 manifest. 



I think it important to describe a few experiments which establish the relation 

 between the intensity of the muscular current and the activity of the respiratory 

 function. I have only been enabled to try these experiments upon frogs, from their 

 great tenacity to life. I have repeated the following experiment several times : I 

 skinned ten frogs completely, and put them into a glass recipient near to another in 

 which were ten other frogs intact. The frogs thus flayed live for six, eight, and 

 even ten hours, and are even quite lively. The muscular current produced by the 

 skinned frogs was always considerably weaker than that of the trogs in their natural 



MDCCCXLV. 2 Q 



