ANATOMICAL FEATURES. The electric organs in all the above-named fishes are to he regarded, according to Wiedersheim, as metamorphosed muscular tracts, and the nerve-endings belonging to them as homologues of the motor end-plates which are ordinarily found on muscles. As re gards the minute structure of the electric organs, the same essential arrangements are met with in all the forms. The framework is formed of fibrous tissue. which gives rise to numerous polygonal or more or less rounded chambers (see Plate). Nu merous vessels and nerves ramify in the connec tive t issue lying between I hese compartments, the nerves being inclosed in very thick sheaths, and having a great variety of origin, according to the In torpedo they arise from the 'electric lobe' of the medulla oblongata, a single branch coning also from the trigeminal; in all psendo-electrie fishes, as well as in Oymnotus. in which over 200 aerVeg pass to the electric organ, they arise from the spinal cord. The electric nerves of ,Malapterurns arise on each side from a single enormous nerve-•ell. which. lying in the
neighborhood of the second spinal nerve. is con tinued into a very large primitive fibre. which passes toward the flat of the tail, dividing as it goes.
The end-o•gans in which the nerves terminate are disks, called 'electric plates,' formed of mus cle-suhstance over one or the other side of which. according to the species. the terminal filaments of the nerve spread out. The side of the elec tric plate on which the nerve brandies out is negative at the moment of discharge, while the opposite side is positive, and thus the different arrangements of the parts in Oymnotus and in Alalapterurus render it clear that the electric shock must pass in different direetions in these fishes—thus, in NIalapte•nrus it passes from the head to the tail, but in the contrary direetion in Oymnotus• In torpedo the olkeharpe passes from below upward. The 1110eliallisIll Whereby the electric plate, become temporarily charged with electricity is not known.