^ 310 PROFESSOR MATTEUCCl'S ELECTRO-PHYSIOLOGICAL RESEARCHES. 



I have also wished to ascertain if the induced contractions continued even when 

 the nerve of the galvanoscopic frog had not been cut. I have therefore prepared the 

 frog, so as to preserve the nerve entire, as follows. Having skinned a frog I remove 

 the viscera, then the bones and muscles of the pelvis, and finally the muscles of the 

 thigh, taking care to preserve the nerve of the thigh. In this manner I obtain a 

 frog whose nervous system is entire, and which has a long nervous filament uncovered, 

 that is, the lumbar plexus and the nerve of the thigh. Having thus obtained the 

 frog, I prepare another in the ordinary manner, which I place upon the turpentine in 

 the manner already described. Then 1 place the nerve of the frog, prepared as has 

 been said, upon the thighs of the other frog (fig. 14.). On exciting the muscular 

 contractions, the induced contractions are obtained as they are by using the galva^ 

 noscopic frog alone ; and at the same time the contractions in the muscles of the 

 back and in the other leg are obtained. We shall have occasion to recur to this ex- 

 periment further on ; we now limit ourselves to deduce from it that the induced 

 contractions are obtained, even when the nerve placed upon the muscles in contrac- 

 tion is entire. 



In using the frog thus prepared, I have experimented upon the induced contrac- 

 tions, by causing the nerve that is in contact with the muscle in contraction to be 

 already in some manner excited by a current or some stimulus. For this purpose I 

 have comprehended the galvanoscopic frog in the circuit of a voltaic circle, or have 

 applied upon the nerve a drop of an alkaline solution. Every time that the inducing 

 muscles are contracted, there is always induced contraction, whether the nerve 

 through which this current is transmitted be already excited or not, and consequently, 

 even when the muscles in which the induced contractions are generated, are already 

 in contraction ; and, in fact, in spite of the contraction already present there is no 

 difficulty in perceiving the induced contraction that follows. 



Many easy experiments may be made to prove that in whatever way the nerve of 

 the inducing muscle be excited, if its contraction fail, the induced contraction is also 

 wanting. I shall limit myself to reporting some of the principal ones. Having cut 

 the nerves at two or three points in the interior of the inducing muscle, so as to pre- 

 vent its contracting, the induced contraction is wanting when the nerve is in any 

 way stimulated external to the inducing muscle. 



If, without cutting the nerve, all the tendinous extremities of the muscles of the 

 thigh are severed, and transverse cuts are also made in those muscles, taking care 

 not to divide the nerves, on stimulating them, the inducing and also the induced con- 

 tractions are wanting. 



By removing with care all the muscles of the leg of a frog, the nervous filament that 

 runs in the leg itself may be uncovered. This nerve may be irritated either with the 

 current or any other stimulus, after having extended the nerve of the galvanoscopic 

 frog upon the muscles of the thigh above. These muscles of the thigh do not con- 

 tract ; the induced contraction is wanting. 



