488 
MR. F. GOTCH ON THE ELECTROMOTIVE PROPERTIES 
second, third, and fourth electrical nerves are homologous to the branches of the 
eighth pair (vagus) in the Skate, whilst the first nerve is said to be homologous to 
the fifth. 
Minute structure of organ .—The organ consists of hexagonal columns extending 
from the ventral to the dorsal surface of the animal. Each column is a connective- 
tissue framework enclosing a number of septa so arranged as to resemble a pile of 
plates in close apposition one to another. The relation of the columns to each other 
is shown in fig. 1, which represents a transverse section through the two organs and 
the body of the animal, the figure being very diagrammatic. 
Fig. 1. 
Transverse section of fish, with organ cut through on each side; about one-fifth natural size. 
The more minute structure of the columns and septa has been investigated by 
Pacini, R. Wagner, Ranvier, and others, for the details of which the work of 
Ranvier (9) gives ample references, and a sj3ecial investigation of the termination 
of the electrical nerves has been made by Ewald (10). Leaving debatable matter on 
one side, it may be asserted that the column contains a large number of transversely 
disposed protoplasmic septa, in which are numerous conspicuous nuclei. The nerves 
enter the column in such a way that the branches lie between the septa. From 
these branches a very large number of finer branches proceed to the ventral surface of 
the septa. The physiological change, which follows the arrival of the excitatory 
nervous impulse, is produced almost coincidently in all the septa, and is of such a 
character that the ventral surface of each septum becomes negative to the dorsal 
surface. It must, however, be borne in mind that when examined in the fresh state 
no distinct surfaces are seen on the septa ; the fluid, which in fresh preparations 
appears to intervene between the septa, being in reality the semi-fluid protoplasm of 
which these consist, in which Brownian movement of granules can be seen even in 
close proximity to the nuclei. 
Physiology of organ .—If we now direct our attention to the physiological side of 
the subject, we find that among the numerous investigations which have been made 
upon the electromotive activity of the Torpedo, those associated with the names 
of Colladon, Matteucci, Marey, and du Bois-Reymond stand out as the most 
important, and the results arrived at by these observers will indicate with sufficient 
accuracy the present position of our knowledge. 
Previous investigations. — The work of Colladon (11), published in 1836, was 
passed by almost unnoticed until du Bois-Reymond, in his treatise entitled “ Lebende 
