SECT. 228.] VITREOUS BODY. 571 



body of man, with the aid of chromic acid), that a number of 

 partitions run from the surface to the axis of the vitreous humour, 

 so that on a transverse section of the eye-ball, made from above 

 downwards, numerous rays are seen to proceed from a central 

 point, the whole structure resembling an orange. In mammalia, 

 however, Hannover has seen concentric lamellae, as in an onion 

 (fig. 237, B). According to Bowman (Lectures, p. 97, fig. 5), the 

 vitreous body of newly-born infants presents, in a well-marked 

 degree, the radiated appearance described by Hannover, when it is 

 prepared by chromic acid j but it is to be remarked, that Bowman's 

 observations point to a somewhat different structure in the eye of 

 the adult, for in chromic acid preparations of such an eye he finds 

 some concentric lamellae at the more external portion of the vitreous 

 body, then very irregular radiating septa, and lastly, an irregular 

 central cavity. "When, moreover, it is considered, that these lamellae, 

 which appear when the eye is treated with chromic acid, cannot be 

 demonstrated as true membranes, and that nothing is to be seen 

 of them in the fresh vitreous body, the appearances produced by 

 this second re-agent cannot be regarded as proving much. 



A more correct view 7 of the composition of the vitreous body 

 appears to be obtained from the history of its development. It 

 has long been known, that the vitreous body of the foetus possesses 

 vessels on its surface and in its interior; and from this it was 

 inferred, that a tissue must be present for the support of these 

 vessels, but until a short time ago, no one had endeavoured to 

 obtain further information on this point by means of the micro- 

 scope. Bowman (Lectures, p. 97, fig. 7, and p. 100) w r as the first 

 to announce, that the vitreous body of the newly-born infant pre- 

 sents a very distinct and peculiar fibrous structure, consisting of a 

 dense network of fibres, with dark nuclear corpuscles at the points 

 of interlacement, so that the structure bears a cansiderable re- 

 semblance to the enamel organ (i. e., to its gelatinous connective 

 tissue) of the embryonic dental sac. Some recent observations of 

 Virchow accord pretty closely with this view. According to this 

 author, the vitreous body of a pig-embryo, four inches long, con- 

 sists of a homogeneous, muciferous substance, slightly striated 

 here and there, and having round, nucleated, granular cells scat- 

 tered through it at regular distances. At the circumference of the 

 body is seen a fine membrane, with very beautiful vascular net- 

 works and a finely fibrous, areolar meshwork, which contains nuclei 

 at the knots, and likewise encloses in its meshes gelatinous mucus 

 with round cells. On account of this structure, and because he 



