ELECTRO-PHYSIOLOGY. 301 



the nerves. To explain that result it was necessary to suppose tbat tlie electric 

 current whicli excites a nerve acts as does the spark of fire wbicli kindles a great 

 mass of powder, or as a small force which cau>=es a heavy mass in an unstable 

 state of equilibrium to fall from a great altitude. It must be supposed, in effect, 

 that when the nerve is excited by the electric current, the excited nerve instan- 

 taneously occasions in the muscle certain chemical actions which, by a concat- 

 enation as yet unknown, are transformed either into heat, or more probably into 

 electricity, and eventually into mechanical labor; in a word, the chemical actions 

 requisite to explain the muscular labor are within the muscle; it is in the muscle 

 that they are produced and exhausted after having been aroused by the excita- 

 tion of the nerve. It was known that a muscle exposed to the air absorbed 

 oxygen and exhaled carbonic acid ; it was known also that exercise of the body 

 enhanced the chemical phenomena of the pulmonary respiration. 



I shall be able to prove to you by a simple and conclusive experiment that 

 muscular contraction is accompanied by an augmentation in the chemical action 

 of the so-called respiration of the muscle — that is, by a greater absorption of 

 oxygen, by a greater exhalation of carbonic acid. Here are two glass bottles 

 of the same capacity, namely, about 100 cubic centimetres each. The openings 

 are closed by a cork stopper, through which pass two wires of iron or copper 

 which are bent horizontally in the interior of the bottle so as to leave between 

 them an interval of twenty to twenty-five millimetres. I hastily prepare ten 

 frogs a la Galvani, and suspend five in each bottle to the wires, by inserting 

 the two extremities of the wires, one in the portion of spine, and the other in 

 the inferior part of the pelvis. Everything should be arranged alike in the two 

 bottles, and the difference will consist alone in connecting the two wires of one 

 bottle with the extremity of an electrical apparatus, b}' which, for four or five 

 minutes, I excite the greatest possible number of contractions in the five frogs 

 of this bottle, while the five of the other remain at rest. After that time I 

 promptly remove the cork stoppers and the frogs, and again close the bottles 

 with stoppers of glass. In order to discover and measure the difference in the 

 composition of the air which has been produced in the bottles, I ought to make, 

 as has in fact been done, a strict eudiometric analysis ; but this is not possible 

 during the delivery of a lecture, and I must, therefore, content myself with 

 showing in a rough but quite evident manner, that in the vessel in which the 

 contractions took place there is much more carbonic acid ^han in that in which 

 the muscles were left in repose. For that purpose I promptly pour the same 

 quantity, ten cubic centimetres of lime water, into the two vessels and shake 

 them. In the vessel where the contraction occurred great discoloration is pro- 

 duced, and consequently there is here a much greater quantity of carbonate of 

 lime than in the other vessel in which the lime water is scarcely whitened. 



It must not be supposed that all the carbonic acid developed by the muscular 

 respiration is exhaled externally. If muscles be placed, after long and repeated 

 contraction, in an atmosphere of hydrogen gas or in a vacuum, it will be found, 

 as some years ago I proved by actual experiment, that those muscles exhale a 

 great quantity of carbonic acid. Bernard, in analyzing the gases of the blood 

 which traverses a muscle after a loug contraction, fouull no longer any trace of 

 oxygen, but nearly all the gas was carbonic acid. It may be said, therefore, that 

 the immediate caixse of the exhaustion of a muscle is an asphyxy, owing to the 

 disappearance of the oxygen as well as of the air of the blood, and to the presence 

 of the carbonic acid which is substituted for them. Perhaps the day is not 

 distant when chemistry will inform us what are the immediate products of the 

 greater combustion which occurs in a muscle through contraction; it is not by 

 the carbon alone that the oxygen is fixed ; the carbonic acid is a last term, and 

 there are, perhaps, also some fixed acids which are produced in that muscle. 

 In fact it has been proved by Dubois Reymond that the acid reaction increases 



