. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 592 bling, when perfectly fresh and unaltered by re-agents, the margin of an oil globule. \\ hen the nerve-tube has been treated with water, or has been allowed to remain a little time on a piece of glass, we observe within the tubular membrane a double-edged layer of a whitish material of different refracting power from either that which occupies the centre of the nerve- tube or the tubular membrane itself. The later after death the nerve is examined, the more dis- tinct does this inner layer become. The addi- tion of w
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 592 bling, when perfectly fresh and unaltered by re-agents, the margin of an oil globule. \\ hen the nerve-tube has been treated with water, or has been allowed to remain a little time on a piece of glass, we observe within the tubular membrane a double-edged layer of a whitish material of different refracting power from either that which occupies the centre of the nerve- tube or the tubular membrane itself. The later after death the nerve is examined, the more dis- tinct does this inner layer become. The addi- tion of water, alcohol, and other re-agents always renders it more evident, and seems to destroy the apparent homogeneousness of the pulpy contents of the nerve tube. This layer within the tubular membrane is that which, according to Schwann, gives to the nerve-tubes their white colour; it is therefore called by him the white substance. Within this and occupying the centre of the tube is a transparent, somewhat flattened, band, which is extremely delicate, and in which it seems impossible to recognize any more definite structure. Thus Remak and others describe three dis- tinct parts in the nerve fibre :—1, the outer in- vesting membrane, tubular membrane; 2, an inner layer of membrane (the white substance of Schwann) lying immediately within the first; 3, a central substance of nervous matter, called flattened band by Remak, and supposed by him to consist of several filaments, or the axis- cylmder of Rosenthal and Purkinje. It is evident that the contained matter of the nerve-tube is extremely soft: it yields under very slight pressure, and may be readily made to pass from one part of the tube to another. When pressed out of the nerve tube, it is apt to assume the appearance and form of globules varying in shape and size, which are easily distinguished from the true nervous globules by the absence of nucleus. Firm pressure will also completely empty the tubular membrane, and thus aff
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