FESSARD: ACTIVITY OF ELECTRIC PLATES 503 



here the presence of inactive tissue around the plates renders illusory 

 any attempt to introduce quantitative measurements. 



C. In observations unfortunately never repeated, Bernstein and 

 Tschermak^" have shown an initial cooling of the organ, when the dis- 

 charge was externally derived through a resistance. They interpreted 

 this fact as being inconsistent with a chemical mechanism of the energy 

 supply. Meyerhof-" criticized this interpretation, without, however, 

 denying the fact, which should be reinvestigated with the more per- 

 fected methods now available. 



D. Recent investigations into the biochemistry of electric organs 

 proved their metabolism to be quite similar to that of nerve tissue or 

 striated muscle. Cholinesterase has been shown to be very abundant 

 in electric tissue (concerning this significant presence of cholinesterase 

 in electric organs, as at all neuronal surfaces, see Nachmansohn^"). 

 This fact implies that acetylcholine plays an essential role here, as 

 elsewhere. 



It was under the impetus of Nachmansohn that research was under- 

 taken by Feldberg, Fessard, and Nachmansohn to detect the prob- 

 able presence of acetylcholine in electric organs, and to study the part 

 it plays in the production of the discharge. In these experiments, posi- 

 tive results were obtained in Torpedo organs. During stimulation, the 

 ester appears in the perfusate, and arterial injections of micro-doses of 

 acetylcholine produce long-lasting electrical changes. ^^' ^® 



The next step was when Nachmansohn and his collaborators" dem- 

 onstrated that cholinesterase is localized at the active surfaces in elec- 

 tric organs, its concentration being strictly correlated with the maxi- 

 mum voltage and, consequently, like the electromotive force, with the 

 number of plates per unit length. Now the acetylcholine release is 

 able to start the chain of reactions, beginning with the phosphorylated 

 compounds acting in nerve or muscle metabolism, which we now know 

 to be present, together with the associated enzymatic system, in the 

 electric organs (Baldwin and Needham,* Kisch,^^ Nachmansohn et 

 al.^^). The research in this field has now reached a quantitative as- 

 pect, and the energy liberated by the breakdown of phosphocreatine 

 and the formation of lactic acid during the discharge can be compared 

 with the electrical energy released (Nachmansohn et oL'^) . 



In concluding this short survey, we can say that there is a striking 

 convergence of data, allowing the electric plate to be put side-by-side 

 with the nerve and muscle units, from the point of view of their electro- 



