. Elements of Comparative Anatomy. 500 COMPARATIVE ANATOMY. The Fishes whicli are provided with these organs belong to the genera Torpedo and Narcine among Rays, Glymnotus among Eels, and Malapternrus among the Siluroids; Mormyrus also has similar organs. There is a pseudo-electric apparatus in Raja. Although these J .-11 Km. rig. 277. A Torpedo, with the electric organs dis- sected out. On the right the surface only of the organ (oc) is shown. On the left side the nerve-trunks jjassingtothe organ are dissected out, and part is followed some way into the organ. The cavity of the skull is l
. Elements of Comparative Anatomy. 500 COMPARATIVE ANATOMY. The Fishes whicli are provided with these organs belong to the genera Torpedo and Narcine among Rays, Glymnotus among Eels, and Malapternrus among the Siluroids; Mormyrus also has similar organs. There is a pseudo-electric apparatus in Raja. Although these J .-11 Km. rig. 277. A Torpedo, with the electric organs dis- sected out. On the right the surface only of the organ (oc) is shown. On the left side the nerve-trunks jjassingtothe organ are dissected out, and part is followed some way into the organ. The cavity of the skull is laid open, and the brain displayed. T Tore-brain. II 'Tween-brain. Ill Mid-brain. IV Electric lobe. V Vagus, ir Trigeminal. </ Its electric branch. 0 Eyes. / Spiracular cleft, t Mucous tubes of the skin. Z)J" Branchia;; on the right they are covered over by a common layer of muscles, on the left the separate branchial sacs are shown. organs differ greatly from one another in position, and in their broader anatomical details, in the dif- ferent genera, they all agree in being com- posed of "alveoli" of various forms, which are bounded by con- nective tissue, and filled with a jelly-like substance. The nerves pass to one surface of these alveoli, where they form fine net- works, and give rise, finally, to an " electric plate,^' which repre- sents the ends of these nerves. The relation of this plate to the whole apparatus, and its. relations to the nerves, are described in the followinsf ac- count of what is seen in the Torpedo. The electric organ (o(?) is placed between the head, the bran- chial sacs (Fig. 277, &/•), and the proto- pterygium of the tho- racic fin; it is as deep as the whole body. and is invested by a tendinous membrane, which is covered by the integument above and below. Each organ is made up of a number of parallel prisms, which again consist of a series of elements set in rows one on the other; these are the above-mentioned alveoli.
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Keywords: ., bo, bookcentury1800, bookdecade1870, bookpublisherlondonmacmillan
