304 PROFESSOR MATTEUCCI'S ELECTRO-PHYSIOLOGICAL RESEARCHES. 



contractions were excited in these frogs. Operating in this manner, I have often 

 remarked the deflection of the needle to be increased by a few degrees, after which 

 the needle retrograded. When the frogs were touched several times with the potassa, 

 or were very much weakened, so that touching them again with the alkali no longer 

 produced contractions, it has, in most cases, occurred that there was no sign of in- 

 creased deflection in the needle of the galvanometer. Finally, bathing the nerves of 

 frogs arranged in piles with acid or saline solutions, the deflection, far from in- 

 creasing, rapidly diminished, at least in the beginning. 



These facts, with which I paused, might have appeared in some manner favourable 

 to the idea that the induced contractions were the effiict of an electric discharge 

 which accompanies the act of muscular contraction : notwithstanding this I termi- 

 nated the chapter referred to with the following words : — " I cannot take upon me 

 to affirm that the question is entirely solved, and I pause here from not knowing how 

 or by what way to advance to solve it." 



The importance, however, of the fact of induced contractions thus always appeared 

 to me very great, and consequently I have not failed to give my strictest attention to 

 the study of it, and I have reason to believe, latterly, with some success. I shall, 

 therefore minutely describe in this memoir all the experiments that I have instituted 

 upon the induced contractions, and I trust the reader will excuse the prolixity of the 

 description. 



Before commencing a fresh series of investigations into the fundamental fact of 

 the induced contractions, I thought it necessary to repeat and vary the experiments 

 of which I have already given an outline, and which were directed to the purpose of 

 discovering whether there is a development of electricity during the contraction 

 of a muscle. In order to have a more fixed and considerable deflection, it was neces- 

 sary to employ piles consisting of a greater number of elements than those I had 

 made use of previously. I imagined that for this purpose a muscular pile would be 

 far preferable to a pile of frogs. I avail myself of this opportunity of referring to an 

 experiment made for the purpose of proving the existence of the muscular current in 

 the living human subject. I applied the nerve of the galvanoscopic frog with care to 

 the muscle of a leg laid bare by a wound. The most lively contractions were excited 

 in the galvanoscopic frog every time that the circuit was suitably closed between 

 the interior of the wound and the surface. 



My late experiments have shown beyond all doubt that, the number of elements 

 taken from the same frogs being equal, the muscular current is much stronger than 

 the proper current. I have recently shown that when from defect of nutrition, a 

 very low temperature, or the action of sulphuretted hydrogen, &c., both the muscular 

 and the proper current of the frog are weakened, the diminution is much more con- 

 siderable in the latter than in the former. And in fact, composing the pile described 

 at p. 116 of my treatise with halves of frogs prepared by cutting the thighs in half, I 

 find a diff'erential current varying in intensity, but always in the direction of the 

 muscular current. It is only in very robust frogs, dividing the thigh in the thickest 



