Structure and Polarity of Electric Motor Nerve-Cell in Torpedoes. 231 



that to which the plasmosome moved. He interpreted this as a symp- 

 tom of the electro-motor activity of the cell. Again, it should be noticed 

 here that he figured all his cells as giving off their neuraxes in a ventral 

 direction and all the plasmosomes therefore as moving toward or 

 orientated toward the neuraxes. This we now know not to be a fact. 

 Figure 4 represents Magini's conception of this orientation. 



In adult examples which were allowed to die slowly out of water by 

 asphyxiation, and which consequently did not give many or violent 

 shocks from their electric organ, Magini found, on the other hand, that 

 the plasmosome was usually central in position, and when eccentric its 

 eccentricity was slight and in various directions. Neither did the 

 crescent-shaped space appear on the dorsal side of the nucleus. 



He also found that in very young 

 specimens (7 cm.), whose electric 

 organs were not yet well developed, 

 the plasmosomes in the electric motor 

 cells were always central. 



He deduced from these three obser- 

 vations that the movement of the 

 plasmosome ("nucleolo") from a cen- 

 tral position in a state of rest to this 

 eccentric position just after extensive 

 and continuous activity was an ac- 

 companiment of the normal and ex- 

 tensive physiological activity of the 

 cell at time of the discharge, and he 

 further concludes that this movement 

 of the plasmosome is the initial phe- 

 nomenon which precedes and causes 

 the nerve action of this cell. (Magini, 

 p. 3.) 



Coggi (8) took issue with these con- 

 clusions, being of the opinion that 

 Magini' s results were artificial and 

 had been due to the osmotic action 

 of some of his fixatives in the cases when the plasmosomes were found 

 oriented in the ventral position, and especially in those cases where the 

 entire nucleus had moved ventrally. The writer, being interested in 

 the American form, Tetronarce occidentalis, in which an undoubted 

 orientation of the plasmosome always exists, carefully studied 24 

 torpedoes at Naples in the winter of 1912-13 and investigated the 

 following points: (1) Is there an orientation of the plasmosome? 

 (2) Granted this orientation, is it due to the temporary physiological 

 activities that initiate those processes in the cell which result in the 

 nervous and the electric discharge? (3) Is it, instead of such a physio- 



FIG. 4. Sketch of a group of electric 

 motor nerve-cells from Torpedo, 

 as described by Magini in the 

 adult after death by vivisection. 



