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PEOFESSOE MATTEECCI’S ELECTEO-PHYSIOLOGICAX EESEAEC'HES. 
tial for induced contraction that the neiTe of the galvanoscopic frog should give signs of 
muscular current at the moment in which it is laid on the thigh. The internal part of 
a muscle may also be used for obtaining this phenomenon ; this is done by immerging 
the nerve of the galvanoscopic frog in a longitudinal wound made in a muscle. From 
this we may infer that a phenomenon of the same kind as that of induced contraction 
takes place on a whole living animal, when an electrical current makes one of the mus- 
cular masses of the upper part of a limb contract : although it may be admitted that the 
nervous filaments concealed in that mass, and which pass through it as they branch 
towards the inferior muscles, are not traversed by the current on account of their low 
conducting power, yet at the moment in which the superior muscles contract, the lower 
ones contract also. This fact, of which 1 treated in the Eighth Series of my Eesearches*. 
appears to be thus traced up to its true cause, namely, that it is a natmul and perhaps 
physiological case of induced contraction. 
I shall add, finally, that when a stratum, however thin, of a good conducting body, or 
a like stratum of a solid isolating body, is interposed between the muscles in contraction 
and the nerve of the galvanoscopic frog, no induced contraction is obtained, as may be 
verified with gold-leaf or an extremely thin lamina of mica; on the contrary, with a 
piece of wet paper, and also with an excessively thin stratum of liquid turpentine, the 
phenomenon continues to manifest itself. 
The many fruitless efibrts which I made, and even the contradictoiy results at which I 
arrived, in endeavouring to determine the cause of induced contraction by means of the 
galvanometer, are well knomi. Although, as far back as 1838, in verifjing the observations 
of Galvani, I had assured myself that when a frog enters into violent contractions, or mto 
a state of tetanus, its muscular current is much weakened, yet I had never succeeded in 
discovering by the galvanometer in a distinct and certain manner, what took place in 
this current during contraction. I am now conwnced, as I shall shortly show, that my 
want of success was due to defective instruments and method. In the Xinth Series of 
these Eesearchesf, having given up the use of the galvanometer, and substituted that of 
the galvanoscopic frog, I succeeded in establishing the true nature of that phenomenon on 
which, the present researches will throw a new light, pro^ing beyond all doubt the jjro- 
duction of an instantaneous electrical discharge in the muscle dming the act of contraction. 
But before proceeding to the exposition of my new researches, it is just that I should 
say to what point M. Du Bois Eeymond has brought this subject. The use which this phi- 
losopher had made of a highly sensitive galvanometer, and of an electro-magnetic inachme 
for exciting sustained contractions, accounts for his having succeeded iu obtaining from 
muscles in contraction a distinct electrical efiect on the galvanometer. The well-knoum 
fundamental experiment of M. Du Bois Eeymond is made by closing the circuit of the 
galvanometer with the gastrocnemius of a frog Avhich remained united to its neiA C ; when 
the needle comes to rest, M. Du Bois Eeymond provokes contractions in the gastrocnemius 
by sending interrupted currents through the nerve : — “ At the moment in which the 
* Philosopliical Transactions, 1850. f Philosophical Transactions, 1850. 
