number of quadrangular and pentangular masses, of minute size and rather irregular form, packed closely together like a mosaic work, arranged vertically, and somewhat resembling a small conglobate gland in appearance. Examined microscopically, it is found to consist for the most part of an abundant, soft, yellowish substance, composed of minute round granules, nearly all equal in point of size, and apparently devoid of nuclei. This granular matter is entangled in an abundant areolar texture, in which, when washed several times, there are to be discovered peculiar nucleated bodies, large, and varying considerably in dimensions, which are at first obscured by the granular matter, and seem to be more or less intimately connected with the small nervous ramifications. Neither when viewed by the naked eye, nor by the aid of the microscope, does this organ in the least resemble the tail electric organ discovered by Stark. Unless the peculiar nucleated bodies already mentioned (and which form indeed a very small part of the mass) be regarded as a modified condition of it, nothing like the "tissue electrique" of Robin exists in the body I have described, while the tail-organ is almost entirely made up of this tissue (Kölliker's Schwamm-Körper).
The nerves supplying the little body which I have described are, first, minute filaments derived from the branches of the vagus going to the gills; and, secondly, a larger one, derived from the posterior branch of the fifth pair, which takes the following course:—If the large branch of the fifth, which is found under the skin immediately behind the temporal orifice, be followed backwards, it will be seen, that after escaping from the cranial cartilage, it gives a branch backwards, which enters the muscle behind it, and, supplying this muscle with several twigs, passes through it to reach the body in question, which it supplies, also giving a little twig to the snout-muscle which covers it.
On carefully inspecting this large division of the fifth pair, the difference of colour is quite obvious between that portion which is destined to go to the ampulla, from which the so-called muciferous tubes take rise, and that portion destined for the muscles; nor is it uninteresting to observe, that the branch going to the supposed homologue of the electric organ is derived from the latter. I need not say that it would be quite impossible to trace so minute a nerve so as to find out whether, at its origin, it may be related to the anterior or posterior columns of the cord; but the fact mentioned tends to support the view that it is related to the motor tract.
As the lateral line system exists in the torpedo and other electric fish, in a rather remarkable condition of development, the opinion held by some authors may be set aside, that it in other fishes represents the electric organs; the same may be said for the so-called muciferous system of rays and sharks (which Geoffroy St. Hilaire conceived to represent the torpedo's batteries), inasmuch as this system also co-exists in the torpedo with the electric organs.
That the tail-organs already spoken of, as discovered by Stark, and since so well anatomised by Goodsir, Robin, Leydig, Ecker, Remak,
