On diseases of the skin / by Erasmus Wilson.

  • Wilson, Erasmus, Sir, 1809-1884.
Date:
1851
Catalogue details

Licence: Public Domain Mark

Credit: On diseases of the skin / by Erasmus Wilson. Source: Wellcome Collection.

    41/608
    nucleated cells, tlie hexagonal and pentagonal forms of the cells being occasioned by their mutual pressure. The relative thickness of the area of the tube and its walls is also indicated. Fig. 18. A group of downy hairs, from the compacted oily substance of an oil-tube: they are magnified 19 times. The peculiar shape of these little hairs is shown in the figure; they are rounded at the ends, and very little smaller in this situation than in the shaft. Their wom-out- paint-brush-li&e roots are also seen. Plate 4. anatomy of the hair. Fig. 1. A small portion of the shaft of a human hair, magnified 310 times. The waving lines caused by the free edges of the overlapping scales are seen, as is their projection along the edge of the hair. The reason of a hair feeling rough when pulled, from point to root, between the fingers, will be perceived at once, on examining this figure. Fig. 2. A small portion of the shaft of a human hair, magnified 310 times, showing the appearance of the fibrous structure. The dark streaks are the seat of colour of the hair, and in proportion to their number the hair is lighter or darker in its degree of shade. Fig. 3. Horizontal sections of hair from the beard, magnified 155 times. In this figure the oval shape of the shaft of the hair is seen, as well as the three portions of a hair, namely, its central pith; the fibrous part surrounding the pith, and constituting the chief bulk of the hair; and its outer transparent thin layer. Fig. 4. A hair from the scalp, showing its position in the hair-tube and its mode of implantation at the bottom of the latter, a. The epidermal sheath of the hair-tube, b, c, cl. The bulb of the hair, composed of cells in process of transformation. At b the bulb separates into two portions, namely, the hair and its enveloping sheath. The figure is magnified 38 times. Fig. 5. A small fragment of the fibrous structure of a hah- magnified 310 times. Fig. 6. A fragment of the pith of a swan's feather, showing its composition of globular cells, very little altered in shape by contact. Fig. 7. Hair of the fallow deer ; magnified 38 times. The middle layer of this hair, instead of being fibrous, is made up of polyhedral cells ; which are simple globular cells pressed into an angular form by contact, like the cells of a honeycomb. These hairs are consequently excessively light and brittle. Fig. 8. A portion of the shaft of a very small pheasant-feather; showing the exact similitude between its pith and the cellulated structure of the hair of the deer.