270 SPECIAL ANATOMY. 



It is rendered neither cloudy nor soluble either by boiling water, or by alco- 

 hol and acids. Of nerves it also possesses, like the lens, a few; and the ves- 

 sels which it shows in a morbid condition are only developed in an abnormal 

 manner. However, Walter has injected vessels on the posterior wall of the 

 capsule. 



The very vascular capsule of the lens in the Embryo (membrana pupillaris, 

 and capsulo-pupillaris) is a closed, delicate membrane, formed of a capillary 

 rete, which at the commencement closely surrounds the lens and its non-vas- 

 cular capsule ; but later, when the eye grows, it becomes smaller in propor- 

 tion to the lens, and is applied to the Iris with its internal border ; the ante- 

 rior portion of the sac is removed from the lens and capsule, and now consists 

 of two halves, namely, the piece which reaches from the border of the lens to 

 the pupillary border of the Iris (membr. capsulo -pupillaris, J. Miiller), and the 

 piece which closes the pupil vertically (membr. pupillaris, Wachendorf). 

 From the seventh month the vessels are obliterated (on the pupillary mem- 

 brane from the centre towards the circumference), the membranes themselves 

 disappear, and the humor aqueus is produced ; in the fossa hyaloidea a few 

 vessels appear to continue in existence. 



504, 3. Corpus vitreum, the vitreous humour, 



a globular, completely transparent body, which consists of a viscous fluid and 

 a membrane (not anatomically demonstrable), filling up the posterior three- 

 fourths of the globe of the eye, is surrounded by the Retina, and receives on 

 its anterior surface, in a depression (fossa hyaloidea), the posterior surface of 

 the lens. At the posterior boundary we find in the fetus an infundibular- 

 shaped fossa, area Martegiaui, which arises from the Art. capsularis, passing 

 in its canal, drawing upwards the vitreous body during the obliteration of its 

 branches (or only arises after death, Arnold). 



Humor vitreus, the vitreous humour, is colourless, and behaves, chemically, 

 exactly like the humor aqueus. It is (probably) placed in cells of the vitreous 

 membrane, which, by punctures, are individually emptied, but nevertheless, 

 perhaps, communicate with each other. In the Embryo it is nourished by 

 numerous vessels, of which, at a later period, the principal trunk only, pass- 

 ing to the fossa hyaloidea, art. capsularis, remains behind. 



Membrana hyaloidea, the vitreous [or hyaloid] membrane, is only visible 

 under the microscope ; it is said to form the cells and the envelope of the 

 whole vitreous body. This envelope is said to divide at the anterior boun- 

 dary of the vitreous body into two lamina?, one of which passes behind the 

 lens, and the other on its anterior surface, so that between the two the 



Canalis Petiti, a triangular, circular, and closed canal, is formed, which 

 surrounds the border of the capsule of the lens like a projecting fold, and pro- 

 bably contains fluid. 



The anterior lamina, strengthened by a fibrous layer of corpus ciliare (on 

 its posterior surface), forms the 



Zonula Zinnii s. corona ciliaris (whether an independent structure or not is 



