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XI. " Electro-Physiological Researches. " Tenth Series. Part I. 

 By Signor CARLO MATTEUCCI, Professor in the University 

 of Pisa. Communicated by MICHAEL FARADAY, D.C.L., 

 F.R.S. &c. Received June 12, 1856. 



(Abstract.) 



In the first section of this part of his Memoir, Professor Matteucci 

 treats of the heat developed by muscles during contraction. Ad- 

 verting to earlier experiments by other inquirers, in which a rise of 

 temperature was observed to take place in the contracting muscle 

 while the blood still continued to circulate through it, and where, 

 consequently, it remained uncertain how far the effect might not be 

 due to a modification of the circulation, the author describes his own 

 experiments, by which it is shown that the muscles of frogs, after all 

 circulation of the blood has ceased, and by the sole act of contraction, 

 cause a rise of temperature amounting to about half a degree Centi- 

 grade. 



The second section is devoted to the consideration of the electric 

 current exhibited by muscles at rest, and experiments are adduced in 

 illustration of the following propositions : 



a. The electro-motive power of a cut muscle is independent of the 

 size of its transverse section. 



b. The electro-motive power increases with the length of the 

 muscle. 



c. The electro-motive property of the muscles of living or recently 

 killed animals is greater in mammals and birds than in fish and 

 amphibia. The duration of this force, which in all cases decreases 

 most rapidly in the first moments after death, is greater in fish and 

 amphibia than in the higher orders of animals. 



d. The nerves have no direct influence on the electro-motive force 

 of muscles. In general, all causes which exert an influence on the 

 physical structure and chemical composition of muscles, so as to 

 modify, in ways unknown, their irritability or contractility, act equally 

 on their electro-motive power. 



Prof. Matteucci here takes occasion to state, that he has verified 

 the important discovery of Du Bois Reymond, of the existence of an 



