31^ PROFESSOR MATTEUCCl'S ELECTRO-PHYSIOLOGICAL RESEARCHES. 



mentioned facts, it remains to me to describe the many experiments I have made for 

 the purpose of discovering the influence of bodies interposed between the muscle in 

 contraction and the nerve of the galvanoscopic frog upon the induced contraction. 

 From my first experiments upon the induced contraction, I had perceived that on 

 extending a sheet of gold leaf, such as is used for gilding, upon the muscle, and then 

 placing the nerve of the galvanoscopic frog upon the gilded muscle, the induced 

 contraction did not take place. That this should happen, it was necessary that the 

 muscle should be completely coated with the gold leaf, which is not the case after 

 one or two contractions when the gold leaf gets torn. I had then seen tliat a 

 varnished paper {papier glac^) interposed between the muscle and the nerve impeded 

 the induced contraction ; and lastly, a sheet of felt soaked with water or the serous 

 liquid that bathes the surface of muscles, and interposed between the muscle and the 

 nerve of the galvanoscopic frog, does not prevent the induced contractions. Our 

 knowledge was limited to these three cases relative to the action of interposed bodies 

 upon the induced contraction. I have therefore sought to extend and vary the ex- 

 periments. The manner of operating that I have adopted, consists in preparing a 

 frog in Galvani's method and placing it upon turpentine ; while an assistant is pre- 

 paring more galvanoscopic frogs whose nerves I extend upon the muscles of the 

 thighs of the first frog. In order to awaken the inducing contraction, I always use 

 a small Faraday's pile of fifteen elements immersed in pure water, and whose elec- 

 trodes are covered with silk and varnished. 



There is no liquid body among the many examined that impedes the induced con- 

 traction ; pure water, slightly acidulated and saline water, serum, blood, olive oil, di- 

 luted alcohol, the varnish of alcohol and resin, volatile oil of turpentine are the 

 liquids made use of in these experiments, and through which the induced contraction 

 takes place. I am always accustomed to let some drops of the liquid under experi- 

 ment fall upon the muscle, and to dip the nerve of the galvanoscopic frog in the same 

 liquid. The induced contraction still subsists even if a thin sheet of felt imbued 

 with the above-mentioned liquids is interposed between the muscle and the nerve. 



The slight conductibility of some of the liquids made use of (oil, oil of turpentine, 

 varnish, &c.) has made me doubt whether the induced contraction would not subsist 

 even in spite of the interposition of an absolutely insulating body. I assured myself, in 

 fact, that across a layer, even very thin, of the said liquids, neither the muscular cur- 

 rent nor the proper one was propagated. On holding the galvanoscopic frog in the 

 hand, and causing its nerve to come into contact with a wetted paper that in any 

 manner communicates with the ground, the contraction, as is well-known, is obtained. 

 The same thing happens on touching with the nerve of the galvanoscopic frog, the 

 muscles either of a frog or of any other animal in communication with the earth. In 

 all these cases it is always the proper current that circulates through the observer, the 

 ground, the touched body, and the galvanoscopic frog. Now if we wet the nerve of 

 the galvanoscopic frog either in common oil, or in oil of turpentine, or in varnish. 



