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PROFESSOR MATTEUCCI’S ElvECTRO-PHYSIOLOGlCAL RESEARCHES. 
of the hirnhar' nerves ought now to he cut ; this being done, we are certain to obtain 
contractions in the galvanoscopic frog, at each contraction of the entire frog; these 
contractions cease if the two legs are brought into communication with the wetted 
cotton, as in the preceding experiment. 
Exp. 9. I take a half fi'og, and instead of the other half, I employ a wick of cotton, 
V, r (tig. 2), one end of which toadies the upper part of the leg or thigh, and the other 
the nerve of the galvanoscopic frog, gp n. The other extremity of this nerve rests on 
the lower part of the leg of the half frog, a thick stratum of wetted paper (o) being 
placed between the nerve and the leg. * Every time that the half frog contracts the 
galvanoscopic frog contracts also ; the latter ceases to contract if one removes the 
upper end (v) of the cotton wick from its contact with the upper part of the leg. It 
ought to be observed, that in this arrangement of the experiment we obtain the con- 
traction of the galvanoscopic frog at the instant that we place the nerve in this sort 
of circuit. 
This experiment has been tried with equal success operating on the limb of a living 
rabbit. 
Exp. 10. Instead of one galvanoscopic frog I dispose two, as in fig. 3, and by irri- 
tating first one lumbar nerve and then the other, I produce contractions in each limb 
separately. During the first moments the two galvanoscopic frogs, c and d, contract, 
whichever may be the limb of the entire frog which contracts. Afterwards, when the 
galvanoscopic frogs begin to be less sensitive, we are sure to obtain contractions in 
the galvanoscopic frog, d, only when the limb a contracts, and the contraction in the 
galvanoscopic frog c, when it is the limb b which contracts. We obtain the same 
result by employing the arrangement adopted in fig. 2, representing the non-con- 
tracting limb by the wet cotton wick, disposed in the manner already described. 
Thus, if instead of having the nerve, gp, disposed as in fig. 2, we reverse the position 
of the nerve of the galvanoscopic frog in such a manner as to touch the cotton wick 
with its upper part, and the point, o, superposed on the limb with its lower part, 
either no contraction at all is obtained, or it soon ceases. 
Exp. 1 1. I cut the thigh of a frog, above and below, so as to form apiece, a h (fig. 4), 
similar to a portion of a cylinder the two circular bases of which are the interior sur- 
faces of muscle. The nerve of the galvanoscopic frog, gp, is disposed on the surface 
of this cylinder so as to be exactly parallel with the two bases. If we irritate the 
point c there are signs of induced contraction. 
It is impossible for me to confine myself to the simple description of these experi- 
ments without deducing from them some conclusions, the most evident of which ap- 
pear to me to be the following : — 
1. The cause of induced contraction, according to all analogies, is the same as that 
which produces contraction of the galvanoscopic frog in the sixth and following expe- 
riments. 
2. The cause of these contractions is evidently an electrical phenomenon developed 
