Ob 1 THE ELECTRICAL ORGAN OF TORPEDO MARMORATA. 
489 
Zitterrochen in Berlin,” drew attention to it and confirmed the main statements 
contained in it. Colladon determined galvanometrically the distribution of electricity 
on the surface of the Torpedo when the animal discharged its shock, a distribution 
which Cavendish sixty years before may be said to have forecast. The results are 
summed up by DU Bojs-Beymond as follows (12) :—■ 
“ (1.) All points on the back are positive to any point on the belly. The strength 
of the current diminishes in proportion to the distance of these points from the organ, 
and almost entirely disappears at the tail. 
“(2.) Any two unsymmetrical points of the back, or any two of the belly, almost 
always yield a current in the galvanometer. The one nearest to the organ is positive 
in the back, negative in the belly. 
“(3.) When contact is made with two symmetrical points either of the back or 
belly, there is no deflection in the galvanometer. 
“ As Colladon was the first to determine the electrical condition of the dorsal and 
ventral surfaces of the Torpedo, I have given the name of Colladon’s currents to the 
currents between points on either of these surfaces.” 
As du Bois-Beymond has shown, the distribution is further modified by the unequal 
length of the columns, every point of the dorsal surface of the organ being positive to 
a point of the same surface which is situated further away from the median edge of 
the organ. The reverse must naturally be the case with reference to two points on 
the ventral surface of the organ. 
Matteucci.— In 1837 Matteucci (13) published his researches on the electro-physio¬ 
logical phenomena of animals, and devoted a large portion of his work to the electro¬ 
motive phenomena manifested by the Torpedo. The earlier observations had been 
made upon the discharge produced in the organ on irritation of the uninjured fish. 
This discharge was therefore a reflex effect, the efferent path of which was clearly 
indicated by the electrical lobes and the large electrical nerves which proceeded from 
these to the organs. Matteucci commenced along the same lines, and ascertained 
that cold abolished and moderate warmth restored this reflex discharge, that after a 
prolonged series of shocks the reflex was so weak as to be inappreciable, but that after 
an interval of rest the discharge returned with all its former intensity. 
He found that a strychnised Torpedo gave a very prolonged discharge which, whilst 
very intense at first, grew feebler and feebler, until, as might be expected, no further 
effect could be detected. 
Division of the electrical nerves or destruction of the electrical lobes completely 
abolished the discharge. He employed both the galvanometer and a much more 
sensitive instrument, the rheoscopic frog, for determining the presence of electromotive 
differences. With the nerve of a nerve-muscle preparation in contact with the 
surfaces of the organ, he found that a rapid electromotive change occurred in the organ 
on division of the electrical nerve, as evidenced by the twitch of the muscle, and that 
this effect occurred whenever the peripheral end of the divided nerve was excited, 
MDCCCLXXXVII.—B. 3 R 
