298 PROFESSOR MATTEUCCI'S ELECTRO-PHYSIOLOGICAL RESEARCHES. ' 



tion, sanguineous circulation, sulphuretted hydrogen) upon the proper current com- 

 pared with the muscular current, I came to the following conclusion : the diminution 

 which occurs in the intensity and duration of the proper current, from the decrease 

 of temperature, from defect of respiration and the sanguineous circulation, and 

 from the action of sulphuretted hydrogen, is considerably greater than that which 

 takes place in the intensity and duration of the muscular current. Thus, with the 

 same number of elements, I have always seen that the proper current has been con- 

 siderably weaker than the muscular current, operating on Yrogs asphyxiated, killed 

 with sulphuretted hydrogen, or in the coldest weather. This difference decreases in 

 proportion to the robustness and vivacity of the frog, so that in the spring and 

 summer, choosing very strong frogs, the signs of intensity and the duration of the 

 proper current equal and even surpass those of the muscular current. 



I was desirous of again studying the proper current in piles composed either of legs 

 alone or of half thighs of frogs, or of entire frogs (figs. 5. 7- 8). In general, as I 

 found before in my former experiments, these three piles produced currents the in- 

 tensity of which was sensibly alike in all. This coincidence seems at first rather 

 singular, considering the diversity of the internal resistance of the three piles, and 

 admitting that the electro-motor element of the proper current resides in the leg alone. 

 The experiments which I shall report at the close of this memoir, explain this fact 

 sufficiently clearly. 



Comparing, however, the three above-mentioned piles, composed from frogs which 

 had been exposed previously to the action of debilitating causes, I have always found 

 that the signs of the proper current, in the pile composed of the legs alone, somewhat 

 exceeded those of the other piles. 



I would here refer to another experiment, described at page 116 of my Treatise, 

 performed with a pile (fig. 6.) of half frogs, from which the upper half of the thigh 

 had been taken away. In this pile the proper current is in opposition to the muscular 

 current, for which reason the current obtained is very weak, and sometimes null. I 

 have still, however, constantly observed that if the frogs employed for thfs experiment 

 are very robust, and in those conditions which we have seen to be favourable to the 

 proper current, the signs of a current which this pile gives, though always very weak, 

 are in favour of the proper current ; while, on the contrary, when the frogs are taken 

 in the conditions unfavourable to the proper current, the slight current which this 

 pile gives are in favour of the muscular current. 



From the sum of these facts I am again forced to conclude, as I was led by my 

 former experiments to do, that the proper and the muscular current are in general 

 subjected to the same laws, and that both these currents vary in the same sense, 

 under the same circumstances. 



But why should the proper current belong exclusively to the frog ? This is the 

 problem the solution of which I had long been anxious to arrive at, and hope finally 

 to have given a satisfactory explanation. 



