. X. PHENOMENA OF THE SHOCK. 201 



exciting and bringing into action the organ in which they 

 are distributed. 



It was important to ascertain what influence the brain 

 exercised over the discharge. For this purpose I exposed 

 the brain of a living torpedo, by making a horizontal inci- 

 sion of its aponeurotic case, and arranged the prepared frogs 

 and the galvanometer upon the body, in order to perceive 

 how r , and at what moment the discharge took place. 



When we irritate the first lobes of the brain (the olfactory 

 lobes) there is no discharge, nor is there if we do the same 

 with the optic lobes, and with the cerebellum. These three 

 iprotuberances of the brain may be removed without the tor- 

 pedo being deprived of the faculty of giving the discharge. 



A fourth part only of the brain remains, which I have 

 named the electric lobe. This can scarcely be touched be- 

 fore shocks take place ; and according as we touch the right 

 or left side, the corresponding organ gives them. We may 

 remove all the other lobes of the brain 'without affecting the 

 electrical function ; but if the fourth lobe be torn, the func- 

 tion is permanently destroyed, although the others be left 

 untouched. 



A fact not less extraordinary is, that when even the tor- 

 pedo ceases to give the discharges, if we irritate this elec- 

 trical lobe, they recommence afresh ; and if we wound it, 

 still more violent shocks ensue, which, in some few in- 

 stances, I have found to have an inverse direction to that 

 which is usual. 



To complete the examination of the phenomena presented 

 by the torpedo, I ought to add that this fish ceases to manifest 

 its electrical properties when plunged into water at about 

 centig. [= 32 Fahr.;] but it reacquires them when put 

 into water at a temperature of + 15 or 20 centig. [= 59 

 Fahr. or 68.] We may repeat these alternatives a certain 

 number of times upon the same animal. 



