New observations upon the structure and formation of certain nervous centres : tending to prove that the cells and fibres of every nervous apparatus form an uninterrupted circuit / by Lionel S. Beale.

  • Beale, Lionel S. (Lionel Smith), 1828-1906.
Date:
1864
Catalogue details

Licence: Public Domain Mark

Credit: New observations upon the structure and formation of certain nervous centres : tending to prove that the cells and fibres of every nervous apparatus form an uninterrupted circuit / by Lionel S. Beale. 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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    3. Further changes in the ganglion-cell after its formation. The ganglion-cell having assumed such forms as represented in figs. 9 & 14, now undergoes further changes. It becomes separated more and more from the point where its formation commenced (figs. 32 & 33, Plate VII.). The two opposite extremities of the cell are drawn down (fig. 34). The fibres increase in length and lie parallel to each other, and the form of the cell becomes much altered. If formed in con- nexion with one of a bundle composed of numerous fibres, the cell seems to grow away, as it were, from the bundle, and sometimes is found at some distance from it, as represented in fig. 41 d; but more commonly its long axis corresponds to the direction in which the fibres of the bundle run (figs. 17 & 21). This is constantly observed in the cells in connexion with bundles of fibres running close to the large arteries in the abdomen; and they may easily be mistaken for cells having a fibre springing from each end. But in this case also the ganglion-cell is some distance from the spot where its first formation commenced, and the two fibres which now extend from it may lie parallel to each other for the distance of four or five thousandths of an inch from the cell, and then take opposite courses in the bundle of nerve-fibres. The ganglion-cell, when fully formed, may lie on the outside of a bundle of nerve- fibres, while the fibre or fibres with which it is connected may run in the central part of the bundle. The two fibres passing from the cell run amongst the bundle of nerve- fibres, to which their course is at first more or less at right angles. Sometimes the fibres from a ganglion-cell pass partly round the circumference of a bundle of nerve-fibres, and then run amongst them. Often the’fibres appear to pass quite to the centre of the bundle. At this point, in fortunate specimens, the two fibres may be seen to alter their course and run with other fibres of the bundle, but in opposite directions (see figs. 32 to 37; also figs. 1, 20 a & c, and fig. 25). As these fibres are often less than the eo.oooth of an inch in diameter, it is very difficult to follow them in the bundle for any great distance; and in ordinary specimens, in endeavouring to unravel the bundle of nerve- fibres, they are inevitably broken. Often they break close to the ganglion-cell; in which case the cell itself, especially if examined in water, appears as a round apolar cell, while the fibres which were continuous with it might be easily mistaken for fibres of con- nective tissue running transversely around the bundle of nerve-fibres imbedded in the neurilemma. Indeed it is probable that many authorities will still maintain not only that the spiral fibre, but that many fine fibres I have described as nerve-fibres really consist of modified connective tissue. If I had only specimens from the common frog, I might have experienced some difficulty in demonstrating that the spiral fibre was a true nerve-fibre to the satisfaction of every one; but many specimens which I have from the green tree-frog settle the question beyond dispute. The spiral fibre is as large and thick as the straight fibre, and, like it, has been traced into a dark-bordered fibre (figs. 1 & 19). Figs. 17 to 28, 31, 38, and figs. 41 & 42 represent different forms of ganglion-cells. c