Observations on the minute structure and mode of contraction of voluntary muscular fibre : being the abstract of a paper read before the Royal Medical Society, Edinburgh, December 15th, 1848 / by W. Murray Dobie.

  • Dobie, William M. (William Murray), 1828-1915.
Date:
[1849]
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the minute structure and mode of contraction of voluntary muscular fibre : being the abstract of a paper read before the Royal Medical Society, Edinburgh, December 15th, 1848 / by W. Murray Dobie. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    Mr. Erasmus Wilson, from an examination of Mr. Lcaland's preparations, whicb he is pleased to call his own investiga- tions,'' describes the fibrilla; very differently; he does not repre- sent any clear lateral edge to the fibril; he considers the clear as well as the dark space to be severally composed of a pair of cells, the dark pair containing a denser myoline than the clear pair; each of these cells is again subdivided into two, thus giving four square cells of equal size in each dark or light interval (fig. 5 a & b). I shall now advert to my own views regarding this structure, which I have deduced from the examination of very numerous demonstrations of the fibrillte, which T have succeeded in making in several kinds of muscular fibre, generally in the perfectly fresh state. • When a favourable specimen of the muscular fibrillse of the frog, pig, or ox, is placed under a microscope magnifying about 500 diameters, and the focus is adjusted with great care to the point at which the fibrillse can be seen with the greatest di- stinctness, or at what I shall term the distinct focus, the ap- pearance presented is the following :—The fibrillar are seen to be divided equally into a series of quadrangular spaces or areas, which are O'bacrvcd to be of two kinds, the one dark, the other clear or light, regularly alternating with each other. The clear area may be observed in favourable specimens to have a distinct edge, and when the fibril has been in no way distorted or stretched, to be continuous with the edge of the dark area. Crossing the clear space at its centre, and at right angles to the length of the fibril, will be seen a distinct dark line ; this line di- vides the clear area into two equal parts or divisions, which are necessarily quadrangular. The dark space in the same focus presents a shape very similar to the clear one, though generally of a more elongated form; its whole sm-face is dark, with the exception however of a clear line crossing it in the same manner as the dark transverse fine does the clear space, and dividing it equally into two dark particles (fig. 6fl). In some cases I have seen the dark spaces divided into three by two clear cross-lines ; an appearanceJJ thinkMiicQcannot be relied on, as the other dark spaces in the same fibrils presented the space as double only, with the single clear transverse line. When the fibrils are stretched, the dark space often appears as if somewhat elevated above the clear space; I have seen this very distinctly in stretched fibrils from the lobster, examined very shortly after death, the clear space having scalloped edges (fig.7«). With regard to the term dark space, it must not be supposed