. Electro-physiology. Electrophysiology. 362 ELECTRO-PHYSIOLOGY CHAP. the central nervous system. This is no less strongly marked at the origin of the " electrical nerves," which arise from two special lobes of the brain, that are wanting in all other fishes. Lorenzini, 1677 (as was pointed out by Boll, 5 d), described these parts as a posterior pair of tubercles, without divining their function, while A. v. Humboldt was the first to recognise them more exactly for the centres of the electrical nerves of Torpedo. After exposing the central organ, they are perceived as two long grayis
. Electro-physiology. Electrophysiology. 362 ELECTRO-PHYSIOLOGY CHAP. the central nervous system. This is no less strongly marked at the origin of the " electrical nerves," which arise from two special lobes of the brain, that are wanting in all other fishes. Lorenzini, 1677 (as was pointed out by Boll, 5 d), described these parts as a posterior pair of tubercles, without divining their function, while A. v. Humboldt was the first to recognise them more exactly for the centres of the electrical nerves of Torpedo. After exposing the central organ, they are perceived as two long grayish-yellow bodies lying close to- gether, from which four nerve-trunks run out right and left, on either side, and supply the organs. According to Fritsch (whose view was also adopted by Schenk on developmental grounds), the dorsally protruding electrical lobes arise from branches of the motor nuclei Fi,;. portion of three of the VRgUS, ill the medulla obloilgata, electrical plates: longitudinal wnich froni the excessive proliferation aspect of the column. (Ranvier.) ol the ganglion-cells that subserve a special function, appear to be pressed upwards from their original seat on the floor of the fourth ventricle. Transverse sections reveal a dense layer of large ganglion-cells, the axis-cylinder pro- cesses of which pass directly into the fibres of the electrical nerves. The character and distribution of the nerves that enter the organ within each single column, or prism, is highly characteristic. As Eudolf Wagner (35) first showed, the fibres all divide up suddenly into many branches before they enter the plates,— forming the characteristic bundle (Wagner's brush—Figs. 230 and 232), of which the spatial distribution, and relations to the single plates, were determined more exactly at a later period by A. Ewald and Fritsch (9). They found th*t the fibres of a brush, about eighteen in number, are superposed upon one another in regular arrangement, entering by the c
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