494 
MR. F. GOTCH OX THE ELECTROMOTIVE PROPERTIES 
In the summer the shallow water of the Bassin d’Arcachon contains many Tor¬ 
pedoes ; but in the winter the fish leave the basin for the deeper water outside. 
There was, however, no difficulty in procuring them, provided the weather was suffi¬ 
ciently favourable to allow the steam trawlers to work. The Torpedoes were found in 
sufficient numbers on the sandy bottom of the sea, at some little distance from the 
shore. They were caught in the trawl, and were, undoubtedly, exhausted by the 
process. Here, however, the cold acted favourably, for, the fish being caught at night 
and kept in tubs on the deck, the temperature was sufficiently low to abolish the organ 
reflex. When brought to the laboratory, the fish rarely showed any movement except 
the winking of the spiracles. Placed in water at 10° C., they recovered, and buried 
themselves in the sand at the bottom of the tanks. They were easily sorted by size 
into small, medium-sized, and large full-grown fish. The small fish were newly-born, 
and measured 13 centimetres in length and 8 centimetres in breadth. Niue of these 
were taken from the uterus : five from one Torpedo, and four from another; the four 
last-named lived for one or two weeks, and were very vigorous little fish. Of 
Torpedoes of this class, eight were used for experiment. 
The medium-sized fish were probably the last year’s young. They measured from 
22 to 25 centimetres in length, and from 14 to 17 centimetres in breadth. Four such 
fish were used for experiments. 
The large fish measured from 40 to 52 centimetres in length, and from 25 to 32 
centimetres in breadth ; of these, seven were used for experiment. 
Although only 19 fish were experimented upon, it must be borne in mind that one 
Torpedo furnishes a mass of material for work, since the organ preserves its excitability 
for many hours when kept in the cold. 
I. Experiments relating to the Organ-Current. 
The organ-current is essentially what in other tissues has been termed a “ current 
of rest.” It has been ascertained by du Bois-Beymond to be present both in the 
entire organ and in cut-out strips of organ as a persistent effect. The current in the 
unexcited tissue has the same direction in the organ as that produced by the response 
of the organ to excitation (the shock) ; that is to say, it is directed through the 
columns from their ventral to their dorsal surfaces. Its amount, though always 
inconsiderable as compared with that of the response, is, like the latter, dependent 
upon the length of the organ columns ; and, consequently, the current has the same 
general distribution over the surface of the organ as the excitatory effect. This is 
thus expressed by du Bois-Beymond : “If we put out of account the smallness of 
the differences of potential, the electromotive surface of the quiescent fish differs from 
that of the same animal when giving a shock only in the induction which accompanies 
the shock” (21). Its presence in small strips of tissue enabled du Bois-Beymoxd 
to calculate the electromotive force of a single plate of a column in the unexcited state, 
