338 ELECTKO-PHYSIOLOGY. 



purpose I place tlie torpedo in a glass receptacle wbicli is filled witli water and 

 exactly closed with a cork stopper ; through the stopper pass two copper wires 

 covered with gutta-percha and inserted in the skin of the fish in proximity to 

 the nerves of the organ; a tube of glass open at both extremities also passes, 

 in which a column of the liquid of the vessel remains suspended as aii index. 

 On irritating the torpedo with the current of an electrfT-raagnetic machine we 

 may be assured that the animal yields the shock by placing also prepared frogs 

 in the vessel. It will thus be ascertained that the discharge occurs without any 

 sensible variation in the volume of the fish. It might be that the volume of the 

 organ Is not altered, as is the case with muscles in the act of contraction, which 

 yet become shortened. To ascertain whether this occurs in the torpedo, I take a 

 lever of straw or very thin glass, with very unequal arms, and restthe extremity 

 of the shorter arm on the fac? of the organ ; it will be seen that in the act of the 

 discharge the extremity of the long arm remains unmoved. 



Let us now inquire what relation exists between the electric function of the 

 torpedo and the nervous action. To evince this relation, the experiments which 

 we have made to prove that the cellule of the electric organ constitutes the ele- 

 mentary electro-motor will suffice. It is known that when the torpedo or gym- 

 notus has given a certain number of discharges it is necessary to allow some 

 time to intervene that the organ may recover its faculty; the organ and its 

 nervous system are exhausted by being brought into action, as are the nerves 

 and muscles by contraction. 



In this connexion it is proper to notice the special function exercised by the 

 fourth lobe of the brain on the discharge of the organ. We have already seen 

 that on irritating the torpedo at any point whatever of its body, the fish responds 

 by an action which proceeds through the medium of the nerves of sense from 

 the irritated point to the brain, and from the brain to the electric organ by means 

 of the large nervous branches which are distributed therein, and which have no 

 other function than that of determining the discharge. The fourth lobe is the 

 centre, in Avhich is collected and from which proceeds the nervous action of the 

 organ, 1 take a living torpedo, in which I rapidly remove the covering of the 

 brain, I distribute prepared frogs on the body of the torpedo, and then, from 

 time to time, mechanically irritate the different lobes of the brain and the 

 spinal medulla. I perceive, on performing the experiment carefully, that it is 

 the irritation of the fourth lobe which specially determines the discharge, and 

 that this proceeds now from the right and now from the left organ, according as 

 I touch at one time the right, at another the left part of the fourth lobe. I re- 

 move entirely the three first lobes of the brain, and divide the medulla elongata 

 immediately under the fourth lobe. The fish now neither renders the discharge 

 voluntarily, nor Avhen irritated in some part of its body ; there is no longer any- 

 thing but irritation of the fourth lobe which gives rise to strong discharges. I 

 have proposed to try, by irritating a nervous fibre uncovered in the middle of 

 the organ, whether the irritation of this fibre ever excited the discharge in that 

 part of the organ corresponding to the centripetal portion of such nerve, but 

 have in no case obtained any sign of this retrogressive excitation of the nerve of 

 the electric organ. Strychnia and morphia kill the torpedo by exciting strong 

 muscular contractions, and at the same time compelling the animal to yield fre- 

 quent discharges. With strychnia the torpedo is thrown into a state of super- 

 excitation, so that the slightest blow given to the surface on which the fish lies 

 occasions the discharge. Poisoned with curare, a torpedo, which no longer 

 yields muscular contractions when its nerves are irritated, does not therefore 

 cease to give the electrical discharge. 



It behooved also to study the influence of the sanguineous circulation and 

 of respiration on the electrical function of the torpedo. Galvani was one of the 

 first who proved that this fish, depleted of blood, continues to yield the dis- 

 charge. The sanguineous circulation is, therefore, not immediately necessary to 



