Volume 1

Elements of physiology : for the use of students, and with especial reference to the wants of practitioners / Tr. from the German, with additions by Robert Willis.

  • Wagner, Rudolph, 1805-1864.
Date:
1841-2
Catalogue details

Licence: Public Domain Mark

Credit: Elements of physiology : for the use of students, and with especial reference to the wants of practitioners / Tr. from the German, with additions by Robert Willis. Source: Wellcome Collection.

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

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    fibres, which are at the same time covered externally with small molecules. In relation with the parietes of the cells, or as intercellular substance, the elastic fibrous net is now produced, and this, from its thickness, raises and incloses be- tween its meshes the smooth dry granular parietes of the cells—this is apparent in the aorta even of adult animals. (c) Muscular tissue.—So soon as the muscular tissue assumes the fibrous form, it is seen to contain very pale round nuclei, lying in the close vicinity of one another. From this it is fair to conclude, that the cells, in like manner longi- tudinally arranged, blend together immediately, and without undergoing elonga- tion into filaments. This inference is confirmed by the circumstance that such a muscular fibre in the embryo is seen as a mere succession of chambers, like a fibre of the ova of the confervse, with its series of cells, and a nucleus in each. I have not hitherto, however, succeeded in obtaining such a view of this multilo- cular arrangement, as fully to satisfy my mind of its entire and constant accord- ance with nature. There are two conditions which either bring out the appear- ance, or render it plainer :—I st. It happens that bet\vixt each two of the ordi- nary constrictions of the muscular fibre a regular nucleus is perceived. 2nd. Upon the transverse lines which produce the cancellate divisions, lie very small round molecules, with very dark outlines and transparent centres, in a more or less regularly transverse lineal arrangement. The clear nucleus lies inside the hollow muscular fibre, and is frequently seen projecting, either partially or wholly, from the divided end of the fibre. At a later period it is ever more and more undistinguishable. Longitudinal strise, and soon after these, transverse striae, make their appearance in the muscular fibre. That the internal hollow of the muscular fibre remains, is rendered probable by the circumstance noticed by me, now some time ago, to wit, that the ends of the living muscular fibre divided, often become everted (Hecker's Neue Annalen, ii. 71). The subsequent stages in the development of the transversely-streaked muscular fibre are treated at length in Entwickelungsgeschichte, S. 69. {d) Fibres of the crystallinu lens.—That the superficial vesiculate or cellular formation suffers metamorphosis into the fibres of the lens, was shown by me to be extremely probable in 1838 (Ammon's Zeitschrift, iii. 330). The cells contain very pale nuclei, with single nucleoli; they then unite longitudinally one with another, like a string of beads, pale nuclei being still discernible inth e cells of most recent formation. Upon the fibres themselves I further observed an extremely delicate granular matter. Each fibre then divides by fine lines into threads, which however cannot be distinctly isolated, even in the adult, and which are remarkable for the beautiful regularity of their arrangement (^Entwick. 203; Werneck, in Ammon's Zeitschr. v. 414). (e) Primary nervous tibre.—Tlie septa arise in the fibres of nerves like those of the muscles, ganghonic globules, and ganglia, glands, &c. out of cellu- late fibres, from which the general sheath of a nerve in the first instance, and the special sheaths in the second, become distinguished. Within this sheath we can perceive, but only at a very early period (in the nervus trigeminus and nervus facialis of the sheep's embryo. If of an inch long, for instance), single primary nervous fibres, which here run as completely isolated as we find them in the pul])y nerves {in nervis mollibus) of adult creatures, which are, like these, rendered visible by caustic alkali (when they are not already obvious), and which from the greater relative strength of the sheath first become tortuous after mechanical