ZOOLOGY. 



MATTEUCCl'S RECENT EXPERIMENTS IN ELECTEO-PHYSIOLOGY. 



Prof. Matteucci, in a letter to Prof. Faraday. May 1, 1856, communicates 

 the results of bis recent experiments in electro-physiology. He says : 



I have lately succeeded in demonstrating and measuring the phenomenon 

 which I have called muscular respiration. This respiration, which consists in 

 the absorption of oxygen and the exhalation of carbonic acid and azote by 

 living muscles, and of which I have determined the principal conditions and 

 intensity compared with that of the general respiration of an animal, has been 

 studied particularly on muscles in contraction. I have proved that this respir- 

 ation increases considerably in the act of contraction, and have measured this 

 increase. 



A muscle which contracts, absorbs while in contraction a much greater 

 quantity of oxygen, and exhales a much greater quantity of carbonic acid and 

 azote, than does the same muscle in a state of repose. A part of the carbonic 

 acid exhales in the air, the muscle imbibes the other part, which puts a stop 

 to successive respiration and produces asphyxy of the, muscle. Thus a muscle 

 soon ceases to contract under the influence of an electro-magnetic machine 

 when it is enclosed in a small space of air ; this cessation takes place after a 

 longer interval of time if the muscle is in the open air, and much more slowly 

 still if there be a solution of potash at the bottom of the recipient in which the 

 muscle is suspended. Muscles which have been kept long in vacuum or in 

 hydrogen are nevertheless capable, though in a less degree, of exhaling car- 

 bonic acid while in contraction. This proves clearly that the oxygen which 

 furnishes the carbonic acid exists in the muscle in a state of combination. 

 According to the theories of Joule, Thomson, c., the chemical action which 

 is transformed, or which gives rise to heat, is also represented by a certain 

 quantity of vis viva, or by an equivalent of mechanical work. I have there- 

 fore been able to measure the theoretical work due to the oxygen consumed, 

 taking the numbers which I had found for muscular respiration during con- 

 traction, and in consequence the quantity of heat developed by this chemical 

 action, and finally this theoretical work according to the dynamical equivalent 

 of heat. I have compared this number with that which expresses the real 

 work which is obtained by measuring the weight which a muscle in contraction 

 can raise to a certain height, and the number of contractions which a muscle 

 can perform in a given time. It results from this comparison, that the first 



