130 
PEOFESSOE MATTELTCI’S ELECTEO-PHYSIOLOGICAL EESEAECHES. 
which the thermometers might be introduced into the bottle. Five frogs were then 
got ready in the usual manner, that is, by cutting oiF the heads, and removing the skin 
and viscera ; when thus prepared and wiped dry, they w'ere fixed on the t«'o copper 
wires by passing these through the pelvis, and the cork with the fi’ogs thus attached, 
was applied to the mouth of one of the bottles. In the bottom of the other bottle I put 
five other frogs similarly prepared, or suspended them on the hooks fixed in the cork ; in 
some experiments instead of frogs I put a little water in the second bottle : the two bottles 
thus prepared with their thermometers, were placed in a room free from cuiTents of air. 
I then observed the two thermometers : after the lapse of some minutes the colunm of 
mercury inserted in the midst of the frogs remained at the same division, or at least it 
was only after the lapse of many minutes that a diminution of -^th of a degree was risible. 
In one of the experiments I found the temperature of the bottle in which there were no 
frogs to be -j- 1 2°' 6 0, while that of the bottle containing the frogs remained fixed at -f- 1 3°' 1 0. 
Then by means of two or three small elements of Daxiell, I set in actirity a little electro- 
magnetic machine constructed by Feoment, remarkable for the uniform sound which it 
produces when the circuit is closed. On connecting this machine with the two copper 
wires which issue from the cork of the bottle containing the frogs, the frogs contracted 
violently from the action of the interrupted current on the lumbar nerves ; almost at the 
same instant the column of the thermometer began to rise, and after a lapse of five or 
six minutes stood at -}-I3°'50. If the experiment is prolonged, this temperature is 
maintained for many minutes. The copper wires used in this experiment must be thick, 
in order to prevent their being sensibly heated by the passage of the cruTent : I assured 
myself of this by direct means, which I shall shortly describe. 
In another experiment, in which the temperature of the bottle without fi’ogs was 
-1-I2°'80, and that of the five frogs -|-I3°’50, the temperature of the latter rose to 
+13° •95. After an hour’s repose I recommenced the experiment on the same frogs ; 
the temperature, which was now +I3°'40, rose only to +I3°‘60 after the renewal of the 
contractions, which were naturally weaker than at first. 
Finally, in another experiment in which there was no sensible difference between the 
temperature of the frogs and that of the air, the temperature of the frogs after four or 
five minutes’ contraction rose from +I3°’55 to 14°, where, as usual, it remained constant 
for a certain time. This experiment was repeated after an interval of fourteen hour's ; 
the passage of the current which had no longer any physiological action produced no 
sensible increase of temperature. 
It is therefore proved that living muscular tissue developes heat hxj the sole act of its 
contraction *. 
* This result may be easily shown by employing, instead of thermometers, two thenno-electric pincers of 
bismuth and antimony, terminating in points. The point of each pair of pincers is introduced into each of 
the severed thighs of a prepared frog. The strips of the same metal of each pincer are brought into com- 
munication, and the other two strips are united to the end of a delicate short-wired galvanometer. On pro- 
ducing contractions, by any means, in one of the thighs, the needle is deflected, indicating heat in the 
convulsed thigh. 
