CHAP. XI.] MATTEUCCl'S PHYSIOLOGICAL RESEARCHES. 375 



Desmoulins et Majendie sur le Systeme Nerveux ; Longet, Anat. et Physiol. du 

 Syste"me Nerveux ; Volkmann, in Muller's Archiv. ; Van Deen, sur la Physiol. 

 de la Moe'lle Epinere, and the works referred to at the conclusion of the last 

 chapter. 



Appendix to the Eleventh Chapter. While the preceding pages were passing 

 through the press, we were favoured, through the great kindness of Prof. Mat- 

 teucci of Pisa, with several opportunities' of witnessing his highly important 

 electro-physiological experiments. As these experiments tend very much to 

 confirm and substantiate the views expressed in Chap. IX., we subjoin here a 

 succinct account of them. 



The facts which M. Matteucci's researches have developed are the following : 

 1 . That muscle is a better conductor of electricity than nerve, and that 

 nerve conducts better than brain. 2. That in the muscles of living animals, 

 as well as of those recently killed, an electric current exists, which is directed 

 from the interior of each muscle to its surface. 3. That in frogs a current 

 exists peculiar to the Batrachian reptiles, which proceeds from the feet to the 

 head, and is distinct from the muscular current. 4. In continuation of Mari- 

 anini's and Nobili's researches, Matteucci illustrates the effects of the inverse 

 and direct currents in nerves of different function, and shews very strikingly 

 the difference in the influence of the electrical stimulus upon nerves, from 

 that of other stimuli upon these organs. 



For these researches, Matteucci employed the galvanometer of Rumkorff 

 (Paris), which is the same as that of Nobili, with the addition of a small ap- 

 paratus by means of which the needles may be rendered more or less astatic, 

 and thus the sensibility of the galvanometer may be more or less increased. 

 But he also takes the precaution to guard against the development of currents 

 by unequal chemical action upon the poles of the galvanometer, to have them 

 made of plates of platina, which is not acted upon by water or saline solutions. 

 He takes two plates of platina, about a quarter of an inch in breadth, and fixes 

 each in a handle of wood. The plates are then soldered to the wires of the 

 galvanometer, and both the handles and the plates are covered with a layer of 

 sealing-wax varnish, leaving only a space of about a quarter of an inch un- 

 covered at the extremity of each platinum plate. 



The frog's leg, prepared in a certain way, is most susceptible of electric in- 

 fluence, and therefore may be used as a galvanometer of extreme delicacy. 

 The skin is stripped off one lower extremity of a lively frog, and the whole 

 length of the sciatic nerve is dissected out from among the muscles of the 

 posterior part of the thigh ; after which the thigh is cut across just above the 

 knee, the nerve remaining attached to the knee and leg. The leg is now 

 placed in a glass tube, in such a position that the nerve hangs loosely from the 

 end of the tube. To use this galvanoscope, the operator holds the glass tube 

 at the opposite extremity to that in which the leg is placed, and causes the 

 nerve which hangs loosely from the tube, to touch at two points the electro- 

 motor element under examination. If the nerve be traversed by a current, 

 the leg instantly contracts. This apparatus, called by Matteucci, grenouille 

 galvanoscopique, is the most delicate we possess, if it be renewed from time to 

 time. And it is capable, not only of indicating the existence of an electric 

 curient, but also of shewing, with a great degree of probability, the direction 

 of that current. When the frog has become a little weakened, it almost con- 

 stantly happens that the contraction takes place on dosing the circuit, if the 



