634 M. Matteucci's Further Researches 



in the substance yielding it, providing phosphate of soda be 

 present. Therefore the researches 1 now take the liberty of 

 criticising do not in any way invalidate the correctness of the 

 generally-received opinion of the presence of alkaline lactates 

 in the different fluids of the body. 



I remain, my dear Sir, 



Very sincerely yours> 

 Guy's Hospital, May 6, 1845. GoLDiNG BiRD. 



LXXVI. Further Researches on Animal Electricity : Of the 

 muscular current and the proper current. {Extract from a 

 letter from M. Matteucci to M. de Humboldt.)=^ 



Pisa, March 27, 1845. 

 TN order to complete all that relates to the muscular current, 

 -^ I shall first observe that I have obtained very distinctly 

 signs of tension on the condenser, at the two extremities of 

 my muscular piles. In the same manner I have obtained the 

 signs o^ electro-chemical decomposition by the muscular current. 

 I have been especially interested in these new researches in 

 studying, in a much more complete manner than I had done 

 in my preceding investigations, the relation between the in- 

 tensity and the duration, after death, of the muscular current, 

 and the activity of the respiration and of the circulation of the 

 blood, the temperature of the medium in which the animal 

 lives, its rank in the animal scale. I have worked at this for 

 five months, submitting to experiment every day a certain 

 number of frogs taken from the same pond. Some of these 

 frogs were immediately killed, to obtain a measure of the 

 muscular current ; others were placed, at the temperature of 

 the external air, in an apparatus by the aid of which I could 

 ascertain the quantity of carbonic acid emitted by a frog in a 

 given time : others again were placed in an ambient medium 

 the temperature of which was constantly at + 16° C. I have 

 operated thus on frogs which had lived from — 4° up to + 16°. 

 The result of so great a number of experiments leaves me 

 not the least doubt on this conclusion : the intensity of the 

 muscular current is proportional to the activity of the respi- 

 ration. I have also operated upon frogs kept for a longer or 

 shorter time in water deprived of air ^ and which were by this 

 means in a more or less decided state of asphyxia. The same 

 result has always been arrived at. 



On operating upon several warm-blooded animals, I have 

 verified in a more complete manner the result at which I had 

 already arrived, that is to say, that the intensity of the mus- 



* From the Comptes Rendus, April 14, 1845. 



