188 Proceedings of Royal Society of Edinburgh. [sess. 
tissue. These filaments are formed by the division of larger ones, 
and, strange to tell, when the filaments of one side of the body 
are traced inwards to the spinal cord, they are all found to spring 
from one single nerve filament which originates in a single gigantic 
nerve cell or neuron. This nerve cell has numerous proto- 
plasmic processes which coalesce here and there to form a per- 
forated plate, in the meshes of which capillaries may be seen. 
These giant electric cells, of which there are two lying side by side, 
one in each lateral half of the cord, and connected by a filament 
passing across the cord, are about the yi-g-th of an inch in 
diameter. We have thus the whole electric organ supplied by 
two neurons, a fact unique in science. Further, the electric 
cells of one half of the body are each supplied by a nerve filament, 
that is to say, there are, in the periphery, 1,000,000 individual 
filaments. These, however, all spring from one nerve filament, 
starting from the single neuron. Fritsch, with praiseworthy zeal, 
measured the diameter of the parent nerve filament, and compared 
it with the sum of the diameters of the million of filaments in the 
periphery. He found that the ratio was as 1 is to 364,000, show- 
ing the remarkable fact of a gradual increase in the amount of 
matter forming the axis-cylinder as we pass from the spinal nerve 
cell to the ultimate nerve fibril. The single electrical cell, little 
more than the T yo-th of an inch in diameter, can thus discharge 
the whole battery on one side of the body. 
Recently Professor Gotcli has had the opportunity of making 
observations with the capillary electrometer on the electric dis- 
charges of this fish, and he has photographed the effects following one 
single stimulus applied to the axis-cylinder. The effect is not one 
electrical discharge, as might have been expected, but eight or ten, 
in a series gradually diminishing in intensity. Here we have a 
kind of electrical reverberation ; and, by a careful study of the time 
relations of these discharges, Gotch is of opinion that the effects 
are chiefly due to changes occurring in the numerous nerve fibrils 
branching off to the electric cells. Suppose we could start a 
Gatling gun by one movement, then the barrels would go off, one 
after the other, as do the electric discharges given off by theRaash. 
These new details of structure also give rise to many difficult 
questions as to the individuality of neurons. Is each neuron a 
