4 V..1. XXXVII., Art. 1.— K. Fuji : 



measured from liead-eiid to tip of tail. Tlic electric organ is present 

 in a pair in the fni-in of hnge flat bodies, situated one on each side 

 iuid lateral mainly to the head and the branchial regions. The 

 upper and lower surfaces of the organ are in direct contact Avith the 

 integument of the flsh. P]ach organ is an assemblage of vertical 

 hexagonal prisms al)out 200 in number. The height of the prisms 

 measures 1-1 -5 cm. Kach prism consists of a pile of disc-like body 

 called the electric jjlalc numberiug about 400. The plates consist 

 each of a clear jelly-like mass inclosing a number of large nuclei 

 and are surrounded as well as separated from one another by a 

 connective-tissue layer in which the nerves and the blood vessels find 

 their course. From the Looks electricus of the brain, there arise 

 on each side five special nerves, the electric nerves, which supply 

 the organ in question. Distally the nerves undergo successive 

 branching, Anally to terminate in fine network on the ventral 

 side of each electric ]:»late. In the discharge of electricity the side 

 of the plate just mentioned is always negative, while the dorsal side 

 Avithout the nerve-endings is positive. 



Before explaining the ])lan of the experiments, we shall 

 describe the method of preparing the organ for the purpose. Except 

 Avhen the spontaneous discharge was to be studied, the organ Avas 

 separated from the l)ody and the Avhole or a part of it Avas used 

 according to eircumstances. When the flsh was brought from 

 the aquarium to the lalioratory, in order to avoid tlie setting in of 

 fatigue, the brain Avas extracted l)y applying a cork-borer to the 

 head and tlien sti'iking its upper end Avith a hannner. The spinal 

 coi'd Avas next destroyed by pushing a Avire into the spinal 

 canal. Having thus avoided tlie reflex action of the nervous centre, 

 the organ Avas separated from the fish. 



The electric dischai-ge of the organ is evidentl_y a very complex 

 phenomenon, for it must be the integral efïect of unit discharges 

 of the electric plates. When a stimulus is given at a point in 

 the nerve-trunk, the excitation is distally transmitted through 

 nerve-fibres of different lengths, and as the speed of transmission 

 through them is finite, it should arrive at the different electric 

 plates not simultaneously l)ut at difïerent periods. Hence it is 



