SOME BASIC ASPECTS OF THE ACTIVITY 

 OF ELECTRIC PLATES 



By Alfred Fessard 

 Institut Marey, Paris, France 



The most conspicuous manifestations of the activity of electric or- 

 gans are: (a) the electrical discharge itself; (b) variations of the elec- 

 trical conductivity of the tissue; (c) thermal effects; (d) chemical 

 (metabolic) transformations. 



Every individual feature of the total discharge is more or less closely 

 associated with the species of fish examined, with its shape and dimen- 

 sions, and with the structural arrangement of the physiological units 

 (or electric plates) composing the organ. However, on the cellular 

 dimension scale, the behavior of these plates shows a striking unity, 

 and is generally considered as an ordinary bioelectric phenomenon. 

 The classical conceptions of nerve physiology are applicable here, and 

 these, combined with our rapidly progressing knowledge of neuromus- 

 cular transmission mechanisms, have been used for explaining the pro- 

 duction of electricity in these organs. Here, briefly exposed for each 

 essential manifestation of activity, are the most significant facts in 

 favor of the unitary conception, together with some details concerning 

 our experimental contribution to this problem. 



A. The most recent determinations of the electromotive force per 

 plate show, on Electrophorus electricus, a fairly uniform value: viz., 

 0.14 volts (Coates and Cox^^). This is in agreement with the highest 

 value found by Curtis and Cole^*' for the action potential from the 

 squid giant axon. As for the time course of the discharge, non-typical 

 shapes are often observed (Cox, Coates, and Brown^^), which may 

 wrongly be considered as representing the elementary process. Our 

 own research in this field has definitely convinced us that these non- 

 typical wave shapes are due to statistical dispersion effects, the causes 

 of which are low velocity at the periphery and differences in length of 

 winding nerve endings. 



In our experiments (most of them still unpublished), we used organs 

 of Torpedo marmorata and of Raia undulata. Our purpose was to 

 record the discharge of a single plate and then to interpret the complex 

 discharges in terms of their components. Columns of electric tissue 



(501) 



I 



