Structure and Polarity of Electric Motor Nerve-Cell in Torpedoes. 247 
The next experiment, on torpedo No. 3, was positive in its results. 
The force used was 543 times gravity for 1 minute. The plasmosomes 
were all moved by an anterior-posterior centrifugal force of this strength 
from varying positions, mostly ventral, to a position in a posterior are 
of about 40 degrees. (See text-figure 6, zg.) In this are the nuclear 
wall is so flat with respect to the direction of the force exerted that it 
makes very little difference in what portion of such an are a plasmosome 
comes to rest, just as the natural force of orientation always brings it 
into the are zy (text-fig. 6), but into any part of that arc. Thus, in 
text-figure 6, we have a diagram representing the outline of a nucleus of 
one of the electric motor nerve-cells with one arrow representing the 
direction of the force of 
gravity and another rep- S 
resenting the centrifugal 
force as applied in this 
experiment on No. 3, as 
well as in other ex- 
periments where greater 
forceswere employed. In 
such a cell the normal po- 
sition of a naturally ori- 
ented plasmosome is at 
1-a, although it may rest 
in any part of the are xy, 
as at 1-b or l-c. When 
centrifugal force is ap- 
plied of sufficient extent 
to change the position of 
the plasmosome it moves U re 
in the direction indicated Fic. 6.—Diagram showing are in which the plasmosome 
by the two-barbed arrow will not move when it arrives from any part of 
“7: the nucleus. 
until it comes to rest on 
the are zg. If the plasmosome starts from l-a, or even from a more 
dorsal position, as 3-a, it will come to rest well in the ventral part of 
the are zg or at 2-a. In this case it rolls along the curved outline of 
the nucleus until the first part of the arc is reached at g, when it stops 
because the angle is too obtuse. If it starts from a median position, 
as at 3-b, or from any position on a median line with reference to the 
centrifugal force applied, as at 3-e or 3-f, it will come to rest in the 
center of the arc zg at 2-b. If it lies in the dorsal half of the nucleus 
as at 3-d or 3-c it will be located by the centrifugal force at 2-c. 
Thus it becomes very easy to estimate the percentage of the central 
orientation of the plasmosome, even after centrifugal force has been 
applied at right angles to gravity and the plasmosome has been re- 
oriented by this new factor. Ventrally oriented plasmosomes will 
become located in the ventral portion of the centrifuged mass of chro- 
matic material as indicated in text-figure 6. 
