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 flat 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 (13), 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? 
