The anatomy, physiology, and diseases of the membrana pupillaris / by Augustin Prichard.

  • Prichard, Augustin, 1818-1898.
Date:
1857
Catalogue details

Licence: Public Domain Mark

Credit: The anatomy, physiology, and diseases of the membrana pupillaris / by Augustin Prichard. 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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    more free anastomosis, miscalled the “ circulus arteriosus iridis minor . The human iris, freed from pigment, is almost trans- parent. In the very dark eye, particularly in those of the coloured tribes, there are pigment-cells scattered upon the anterior surface, in addition to the uvea behind; but, in the blue or light coloured iris, there is no pigment in front: the colour is due to the reflection of the light through the trans- parent iris from the uvea, the light being decomposed, and colour thus developed by the finely divided surface of the membrane ; and when the pigment has been removed by washing, there is no appreciable difference in colour between an iris that was originally blue and one that was grey, or green, or light brown. In the human foetus, there are vessels upon both surfaces of the iris. The posterior set passes as far as the pupillary margin, and not beyond; whilst the anterior run onwards in a straight course upon the membrana pupillaris, and, turning round at a little distance from the pupil, pass back to gain another part of the membrane, but still upon the anterior surface. In an injected foetus of about six months, the membrana pupillaris is seen in perfection. The iris is narrow, and not fully developed; the pupil is large; and the membrane is thin, transparent, and covered with fine vessels, visible by the naked eye, particularly if it is stretched upon a white surface. (Fig. 1.1 Fig. 1. The iris and membrana pupillaris of a six months foetus. The anterior vessels of the iris are here shewn to be continuous with those on the membrane, and one vessel is seen to traverse the centre. These vessels form a series of loops upon the membrane, and occasionally one traverses the centre. Cloquet, in his memoir