288 PROFESSOR MATTEUCCl'S ELECTRO-PHYSIOLOGICAL RESEARCHES. 



and substituted hydrogen gas in its place. After the circuit had been closed ten 

 minutes, the needle of the galvanometer remained stationary at 1,5°. But then in- 

 stead of continuing to retrograde it began to advance, so that the deflection was 50° 

 at the end of ten minutes. 1 broke the circle by drawing the rod up, and when the 

 needle had returned to 0° I again completed the circuit ; the needle now advanced 

 to 90° in the usual direction of the muscular current, and remained fixed at 55°. 

 From this point the needle of the galvanometer descended very slowly, being at 40° 

 at the end of an hour. I then exhausted the hydrogen and re-admitted air, and the 

 needle returned to 12°, continuing to recoil, but still more slowly than in the other 

 experiments. 



I repeated this same experiment witli precisely the same results ; that is to say, the 

 needle descended as usual before the hydrogen was let into the receiver ; after the in- 

 troduction of the gas it advanced to 50°. I then produced a vacuum and again ad- 

 mitted the air, and the needle again descended, still however keeping up a greater 

 deflection than there would have been if the hydrogen had never been used. I have 

 been able, several times with the same pile, to observe the alternations of the effects 

 produced by air and by hydrogen gas. Prolonging the contact of the hydrogen 

 for some time, I have constantly observed that when that gas was exhausted and 

 atmospheric air substituted for it, the final deflection of the needle, taking into ac- 

 count the time elapsed since the preparation of the pile, and cceteris paribus, was 

 much greater than it would have been if no hydrogen had been introduced into 

 the receiver. Finally, I will mention another experiment performed by closing the 

 circuit with the usual muscular pile after having filled the recipient with hydrogen. 

 The first deflection was the usual one, and then followed 47°, 41°, 40°, 38°, 3/°, 35°, 

 34°, 32°, 31°, 30°. These signs of deflection were noted down at intervals of ten 

 minutes. After six hours the needle was stationary at 25°. When hydrogen is 

 not used, that is in atmospheric air, in vacuo, or in oxygen, the deflection does not 

 exceed 5° with the usual pile of twenty elements, after the circuit has remained closed 

 an hour. 



Although 1 could not attribute this singular diffbrence produced by the presence 

 of hydrogen upon the muscular pile to the action of this gas upon the source of elec- 

 tricity in the muscles, nevertheless it appeared to me important to discover the cause 

 of this difference. I very quickly prepared forty elements (half thighs of frogs), using 

 every possible precaution to have all those circumstances equal in all the conditions 

 which are known to influence the muscular current. Thus, two individuals prepare 

 the frogs at the same time, each frog is divided into halves, and two separate heaps 

 are made, from each of which twenty elements, or half thighs, are selected. I leave 

 twenty of these elements exposed to the air, and the others in an atmosphere of hy- 

 drogen by means of the receiver. 



At the expiration of forty minutes I take these twenty elements out of the hydrogen, 

 and compose the pile, and I do the same with the other elements left in contact with 



