Page:Plates illustrating the natural and morbid changes of the human eye.djvu/29

Rh work of light yellow lines. These are the nearly empty transparent veins (vasa vorticosa) of the choroid.

The irregular-shaped greyish patches intervening between the veins of the choroid, represent groups of stellate pigment cells.

These groups, as regards their shape, are normal, and care has been taken to represent their shape correctly.

In health their colour varies (in the merely anaemic choroid) between a light and a dark brown, or nearly black.

The few black patches to the right of the optic disc, somewhat resembling bone corpuscles in shape, are supposed to be groups of pigment granules, derived from hexagonal cells, and to be situated some in, some beneath the retina.

PLATE VIII.

Fig. 19. The region of yellow spot of the eye, of which Plate VII. Eig. 18 represents the optic disc, &c.

The shape of the groups of stellate pigment cells represented in the figure is different from those shown in Plate VII. Eig. 18. The red colour, occupying about two-thirds of the figure, is attributed to blood circulating in the veins and capillaries of the choroid.

To the right (over the more anaemic portion of the choroid) we see a thin vessel of the retina, and to the left a few black pigment spots of the same kind as described in Plate VII. Fig. 18.

Fig. 20. Anæmia with atrophy of the retina and choroid. A portion of the retina, choroid and sclerotic from the upper equatorial region of the eye.

The brownish-black spots represent groups of pigment granules from hexagonal cells, and the grey oblong patches groups of stellate pigment cells.

The turbid brown red colour, represented in the figure towards the right and left of the groups of stellate pigment cells, is caused by the