File:Electro-physiology (1896-98) (21199671442).jpg

Title: Electro-physiology
Identifier: electrophysiolog02bied (find matches)
Year: 1896-98 (1890s)
Authors: Biedermann, W. (Wilhelm), 1852-1929; Welby, Frances A. (Frances Alice)
Subjects: Electrophysiology
Publisher: London : Macmillan
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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348 ELECTRO-PHYSIOLOGY CHAP. It is evident that not merely the muscle-fibres corresponding with the plate, but those surrounding it also, would be similarly excited ; under normal conditions, however, this is experimentally found not to be the case. Moreover, the lines of current traverse the adjacent fibres at right angles to the long axis, i.e. in the ineffective direction. There are certain artificial, and therefore a priori improbable, conditions under which such a distribution of potential might come about in the plate, " that the resulting current through the corresponding fibres should be perceptibly denser than in the adjacent fibres," but these commend themselves the less in that they at once destroy analogy with the electrical plate. It is, e.g., conceivable that a P.D. should arise at the under-surface only of the end-plate, on excitation (Fig. 228); this would then
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t at the moment of discharge form " a mosaic of positive and nega- tive points, between which only molecular currents circle, and these, at a distance equal to the least diameter of the plate, would be of imperceptible density." Considering further that the facts of comparative histology of the motor nerve-endings are in direct contradiction with the theory of discharge, since the presence of true typical end-plates appears to be confined to the muscles of the higher vertebrates, a few fishes, and insects, the theory in its original form is hardly tenable. Du Bois-Eeymond accordingly proposed a " modified theory of discharge " ; but this is scarcely more acceptable than the first, since its postulates are equally inadequate. " Definite anatomical relations are required to account for the inefficacy of the process towards adjacent muscle-fibres, and should consist in a slight, hook-shaped curvature of the extreme end of each hypolemmal nerve-fibre on to the surface of the con-

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