Structure and Polarity of Electric Motor Nerve-Cell in Torpedoes. 237 



The table on page 236 gives a summary of the list of the torpedoes 

 experimented upon, with their sizes (length in centimeters) , the mode 

 of killing, and the amount of ventral orientation of the plasmosome in 

 the nucleus, found in each case by counting 200 cells and estimating 

 the percentage as follows : the nucleus was roughly divided by the eye 

 into an upper and a lower half in each of the 200 cells counted. The 

 number of cells with the plasmosome in the upper half (always smaller) 

 was subtracted from the number with the plasmosome in the lower half 

 and the percentage which this difference was of the entire 200 was 

 assumed as the percentage of differentiation or ventral orientation in 

 the specimens under consideration. This seemed to be a fairly accurate 

 method for this purpose. 



A few remarks must first be made as to the amount of "shocking" 

 or electrical discharge performed by the fish under each method of 

 killing. Cutting (vivisezione), as mentioned by Magini, was performed 

 in 14 cases. This method was fairly quick, being hastened in order not 

 to deliberately torture the fish to any great extent. It was considered 

 by the writer that the usual stimulation, and teasing or worrying, which 

 resulted in numerous strong shocks, produced as decided and charac- 

 teristic physiological activity as that produced by torturing with the 

 knife. However, even when killed by quick, deep slashes which cut 

 the gills and the spinal cord and separated the upper brain from that 

 part which bears the electric lobes, enough strong shocks were given 

 to satisfy Magini's condition of " vivisezione," and when the fish was 

 sharply teased, frightened, and worried before this until the shocks 

 began to weaken, it appears certain to the writer that any visible 

 material effects on the nerve-cells, due to an immediately previous 

 large discharge of electricity, must become apparent. 



As Magini has said, when a torpedo is allowed to rest in a tank and 

 is then taken from the water very quickly and cautiously by slipping 

 a dissecting board under it and raising it out and on to a table and 

 leaving it there for several hours until death has ensued, then the fish 

 dies without giving practically any shocks. This was found to be true 

 in nearly all cases. 



Poisoning the fish in any way was not a success, as with most poisons 

 it gave electric discharges of considerable strength, but not enough to 

 make one feel that the motor electric nerve-cells would show any 

 effects. With chloroform the result was of particular interest because 

 the fish remained quiescent under this drug, carefully administered, 

 until all muscular action of the tail and fins had ceased. . Then, in what 

 the writer takes to be the critical period, when death finally arrives, 

 the fish gave about 90 to 100 single, fairly strong shocks, each of which 

 was spaced from the one preceding it and that succeeding it in a way 

 that led him to believe each one to be correlated with a single heart- 

 beat. No galvanometer was available to correctly portray this process, 



