File:General physiology of muscles and nerves (1881) (14754702646).jpg

Identifier: generalphysiolo00rose (find matches)
Title: General physiology of muscles and nerves
Year: 1881 (1880s)
Authors: Rosenthal, I. (Isidor), 1836-1915
Subjects: Physiology Muscles Nerves
Publisher: New York, D. Appleton and company
Contributing Library: Columbia University Libraries
Digitizing Sponsor: Open Knowledge Commons

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, together with the length of thepassage between the point irritated and that at whichthe current is diverted, it is evidently possible to calcu-late the rate of propagation of the negative variationwithin the nerve. Bernstein in this way determinedthe rate at 25 m. per second. This value correspondsas nearly with that found for the propagation of theexcitement in the nerves (24-8 m.; see ch. vii. § 3) as 220 PHYSIOLOGY OF MUSCLES AND NERVES. can be expected in experiments of this nature; and itmay be unconditionally inferred from this correspond-ence that negative variation and excitement in the nervesare two intimately connected and inseparable processes,or rather two aspects of the same process observed bydifferent means.^ 5. The negative variation of the nerve current isnot the only electric change known to occur in nerves.Under the name Electrotonus we have already (ch.viii. § 1, p. 125) mentioned certain changes in the ex-citability which occur in the nerve iibre as soon as an
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Fig. 60. The changes in tension during electeotonus. electric current is transmitted through a part of it.These changes in the excitability correspond withchanges in the electric condition of nerves, which wecalled electrotonic. In fig. 60, 71 urepresents a nerve,a and k two wires applied to the nerve through which anelectric current is transmitted from a toward k; a istherefore the anode, k the kathode of the current em-ployed for the generation of electrotonus. As soon asthis current is closed, all the points of the nerve on theside of the anode (from n to a) became inore positive,all on the side of the kathode (from k to n) more See Notes and Additions, No. 12. ELECTROTONUS. 221 negative than they were. These changes are not, how-ever, the same in degree at all points; the change isgreatest in the immediate neighbourhood of the elec-trode, and decreases proportionately with the distancefrom this. If the degree of positive increase from ato n is indicated by lines, the height of whi

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