General physiology; an outline of the science of life . Fig. 123.—/. Torpedo marmoratus ; the skin is partially cut away so that the electric organ, a, isvisible ; it consists of numerous polygonal columns, which are here seen in cross-section.(After Ranvier.) //. Two electric columns from the torpedo seen en face with the electricnerves branching over them. (After R. Wagner.) The electric organ of the torpedo is composed of numerouslong columns, hexagonal in cross-section, which correspond to 270 GENERAL PHYSIOLOGY muscle-fibres (Fig. 123). Each of these columns is composed oftransverse discs
General physiology; an outline of the science of life . Fig. 123.—/. Torpedo marmoratus ; the skin is partially cut away so that the electric organ, a, isvisible ; it consists of numerous polygonal columns, which are here seen in cross-section.(After Ranvier.) //. Two electric columns from the torpedo seen en face with the electricnerves branching over them. (After R. Wagner.) The electric organ of the torpedo is composed of numerouslong columns, hexagonal in cross-section, which correspond to 270 GENERAL PHYSIOLOGY muscle-fibres (Fig. 123). Each of these columns is composed oftransverse discs lying symmetrically upon one another (Fig. 124, A);these are exactly homologous with the cross-striation of the muscle-fibre, but do not possess doubly refracting elements, and do notundergo changes of form during activity. Still greater is thecorrespondence in structure of the electric columns and cross-striated muscle in the half-electric or pseudo-electric fishes, ,Eaja clavata (Fig. 124, B). A very interesting and obvious change. t: £ sms Mumuiikas ? ? * i i nM WW<*(W# HM i Fig. 124.—A. Two electric columns of Gymnotus electricus. (After Schultze.) B. I. Columns fromthe pseudo-electric organs of Raja clavata. II. a and b. Single segments of I, more stronglymagnified ; the left half in ordinary light, the right half in polarised light. (After Engel-mann.) of function is here presented, for the electric organs develop outof genuine, contractile, cross-striated muscle-fibres ; and, as contrac-tility is lost, the electric properties come into greater similarity with the muscle is also evident during the activityof the completely-developed organ; for just as the muscle in asingle twitch gives only a brief current, so in the electric organthe current is momentary, although of incomparably greaterstrength. ELEMENTARY VITAL PHENOMENA 271 The above picture of the transformation of energy in living-substance is as incomplete as was that of metabolism. As i
Size: 1357px × 1842px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookidgen, booksubjectphysiology
