Licence: Public Domain Mark
Credit: On the peripheral nervous system / by Samuel Rhind. Source: Wellcome Collection.
Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.
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![atti’action of the contractile tissue, it passes tlirough its sheath, now unahle to prevent its escape, as (and I only use it as an illusti'ation) the electric fluid passes tlu’ough a had conductor to gain . any body which has a superior attrac- I tion for it. If the fibre loses its sheath I entirely, then, of course, no such ex< ] planation is needed. With regard to I tire sympathetic fibres the case is far (different; for since they have no sheath, i it follows that their' fmrctional relation- s ship witlr the organic muscidar tissue is f exactly the same as their anatomical: , consequently, the motor impulse is com- imrrrricated to more of the contr'actile f fibres, and through a greater portion of ttheir length it is thus weakened; and tthus can be explained the slow con- ttiirued contraction of tlrese fibres. In sshort, whilst the anatomical relation cof the cerebro-spinal fibre bears no pro- portion to its functional relation with rmuscular tissue, m the sympathetic both aare equal: of corrrse the gr-eat influence tthat the difference of intimate structirre iTof the two varieties of muscular tissues oexercises in causing the two forms of .'contraction, is not forgotten in the above oobservations. The views expressed in tthis paper are quite consistent with that beautiM theory,—namely, that a nerve fibre has the inherent power of prevent- ling the escape of an impression, tiU it c comes into relation with that tissue ^with which it is functionally related. jThis is evident on a little reflection, so tthat I will not further comment on it. If we hold this view,—namely, that inerve fibres have an inherent power of rretaining impressions in their true ccourse, we need not have recourse to ithe view hinted at by Messrs. Todd and IBowman, that the white sheath is an isolate!' of impressions, since the sur- rounding tissues would have no attrac- tion for them, and so themselves would act as isolators. Whilst wo hold this as sound physiology, yet we must remem- ber, however, that one fibre which wo may suppose to be conducting an im- pression, is su!TO!inded by many others capable of conducting in the same direc- tion. I would therefore ask,—May not the sheath in the course of cerebro-spinal fibres have the office of preventing any communication between fibres them- selves conducting in the same du-ection, and may not the absence of the same in the sympathetic allow of such com- munication ? This question I ask cau- tiously, knowing that it ratlier clashes with received views; there are, indeed, some things which militate against it, yet, I think, after we have carefully considered everything, there is that which makes it sufficiently probable to warrant fur- ther attention. It will be at once evident that such a view would help us much in considering the relative func- tions of the two great divisions of the nervous system. I have in this paper endeavoured to point out that jrortion of a nerve fibre which should be regai'ded as its periphei'y, in distinction to its couise. I do so cautiously, knowing that there are facts which might bo urged against such a view. As far as I know, this has not been made the subject of special investigation before; enough, I conceive, has been said to warrant fm'ther inquii-y ; for it must occur to evei-y reflecting mind, that we might expect to find a special peripheral arrangement in fibres for the detection and communications of impressions, just as we do a special centr'al appar-atus to receive, reflect, or transfer such.](https://iiif.wellcomecollection.org/image/b22424635_0007.jp2/full/800%2C/0/default.jpg)
