508 ANNALS NEW YORK ACADEMY OF SCIENCES 



II. ORIGIN AND LOCALIZATION OF THE ELECTROMOTIVE 



FORCE 



These are largely a matter of speculation, as they now concern the 

 level of molecular organization. Thermodynamic data on one hand, 

 experiments with microelectrodes on the other, would be most useful. 

 Awaiting these, we must content ourselves with discussing the points 

 on v/hich experimental results are available: for instance, the most im- 

 portant problem of plate polarization in the resting state. 



a. The classical hypothesis is that of Bernstein.'' This postulates a 

 permanent superficial polarization of the plate boundaries. The arrival 

 of a nerve impulse results in a local transient annulment of this polari- 

 zation, in accordance with the general assumption. Now, only one 

 side of each plate is innervated and capable of being depolarized. As, 

 at rest, the potential difference between the two extremities of an elec- 

 tric organ is approximately zero, in spite of the coupling in series of 

 the plates, one must suppose an exact compensation of the electromo- 

 tive ft)rce developed on one side of each plate by that developed on the 

 other side (figure 2, Schema I). We thus arrive at that strange con- 

 ception of two distant polarized layers, endowed with different prop- 

 el ties and yet electrically charged in exactly the same way. Their 

 properties are different, because one is supposed to discharge itself 

 through a sudden internal leak due to collapse, while the other starts 

 discharging without collapse into the external medium. Yet not a 

 sign of a double evolution of potential can be observed in the course 

 of the elementary discharge. On the other hand, these opposite layers 

 are not situated in similar regions, from the point of view of tissue 

 structure and chemical environment. It is very unlikely that they 

 should develop the same electromotive force. 



b. Another hypothesis has been recently proposed by Cox, Coates, 

 and Vertncr Brown,' '^ who assume a constantly present electromotive 

 force, non-compens.ited by another opposed electromotive force, but 

 hidden by tlie high resistivity of an interface. This is not conceivable, 

 in our opinion, without caj^acitive properties by which the interface 

 appears as passively charged (fijure 2, Schema ITl. According to the 

 present concept, "the discharge would be started by a very large and 

 rapid drop in the resistance." We have seen that this drop in resist- 

 ance really exists, but we cannot conceive of the resting voltage, sup- 

 posedly present, being lowered, say from 500 volts to 5 millivolts, by the 

 simple interposition of biological membranes, the resistances of which 

 are, at the highest estimate, 1000 ohms/cm.^ in the nerve interfaces 



