Structure and Polarity of Electric Motor Nerve-Cell in Torpedoes. 241 



take place in the functional axis of the nerve-cell. Among such activ- 

 ities we would have to consider the movement of nuclear matter out 

 of the nucleus into the cytoplasm to become or to help form the chromo- 

 phyllic substance, the respiratory and nutritive processes connected 

 with the discharge, and the performance of the discharge itself. 



Again, and a stronger point, we find that in many fish, of all ages (or 

 size), there is practically or actually no orientation at all. This would 

 seem to settle the argument. It can not be a necessary condition of 

 functional activity. 



We now find ourselves ready to consider two possible immediate 

 causes of the orientation, both of which are simple physical factors 

 and are conditions affecting the cells only during the individual life 

 of the animal. One of these is the electric current in which the cells 

 lie at the time of each discharge of the electric organ, and the other 

 is the force of gravity which, owing to the fiat shape of the fish and 

 its sluggish habits, exerts its power on the cells and all their parts 

 in a definite direction during its entire life from birth on. We will 

 consider the electric current first. It has already been explained 

 about the fish's own current passing through the brain, but the writer 

 may be pardoned for repeating this explanation with more detail at 

 this point. 



Cavendish (7) was the first to examine the different parts of the body 

 of the torpedo and of its surrounding media and to plot a series of lines 

 representing the courses taken by the electric currents that it generates 

 (see text-figure 1). 



Dubois-Reymond, working on the electric currents developed in con- 

 nection with the shock given by Malopterurus (IS), showed undoubtedly 

 that the currents flow in part through the animal's body, and with 

 a strength that is comparable to the currents developed in the sur- 

 rounding medium. 



Boll, in a very thorough research on the torpedoes (4), improved on 

 Cavendish's work and showed the same electric-current lines that this 

 author described in greater detail. The point to be noticed in his 

 work in connection with this paper is that the current curves pass 

 not only through the surrounding water, but a good part of them also 

 pass through those parts of the fish's body that are not occupied by 

 the electric organ. Owing to its position in the body, this is particu- 

 larly true of the brain, including the electric motor ganglia, in which 

 are the cells under discussion in this paper. (See text-figure 2.) 



This means that during every discharge of a torpedo, given while 

 under water, a current is passing downward through the brain or in 

 the opposite direction to its course as generated in the electric organ 

 itself. The question is: does this current, operating at intervals during 

 the life-time of the animal, exert any influence on the plasmosome that 

 would account for its orientation in those cases where orientation occurs? 



