File:American journal of physiology (1898) (14597665509).jpg

Identifier: americanjourna13ameruoft (find matches)
Title: American journal of physiology
Year: 1898 (1890s)
Authors: American Physiological Society (1887- ) American Physiological Society (1887- ). Abstracts of papers presented at the fall meeting American Physiological Society (1887- ). Proceedings
Subjects: Physiology Physiology
Publisher: (Bethesda, Md., etc.) American Physiological Society (etc.)
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: University of Toronto

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reater in the stretched tJian in the relaxed condition of the worm,although the amplitude of the muscular response remains the same.Unless the extension of the worm amounted to actual stretching, atleast of the posterior end, this difference in the latent time did notappear. In no instance did the stretching diminish the latent time. Fluidity of the Conducting Substance in Nerve. 355 The close similarity in rapidity and strength of contraction of thehead end of the preparation in the two conditions is shown by thetracings reproduced in Fig. 2. It must be admitted, however, that the question whether theincreased latent time is exactly counterbalanced by the additionallength of the nerve-cord, so that the rate of conduction of the im-pulse remains exactly the same, cannot be answered with absolutecertainty, because of the difficulty of obtaining accurate measure-ments of the length of the nerve-cord in the relaxed worm. Thelength of the nerve-cord in the relaxed worm is probably not far
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Figure 2. Tracings from the contraction of the head end of the worm (Bispira) ou stim-ulation of the nerve-cord at the posterior end with a single induced shock. A, wormrelaxed. B, worm stretched. Time : 100 d. v. per second. Difference in latentperiod between A and B, 0-01 second. from the length of the worm after being killed in fresh water. Atany rate, the nerve-cord does not appear to be in loops in the wormthus killed. Taking the length of the worm after being killed inthis manner as the actual length of the nerve-cord in the relaxedcondition of the preparation, the rate of conduction of the impulse inthe stretched and the relaxed series in Table I is nearly the same.Some of the series in Table II show greater variations, probablyowing to faulty measurement of the length of the cord involved.The average rate for all the series in Table II gives 630 cm. persecond for the stretched nerve-cord, and 585 cm. per second for therelaxed nerve-cord. The slightly lower figure for the nerve

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