THE VITREOUS BODY. 



731 



On the structure of the retina may be consulted Heinrich Miiller, in Siebold und 

 Kolliker's Zeitschrift, 1851 and 1856; M. Schultze, "Obs. de retinae Struct, penit.," 

 1859 ; Goodsir, in Edin. Med. Journal, 1855 ; Kolliker, Handbuch d. Gewebelehre, 

 4th ed., 18(53 ; and Henle, Handbuch d. System. Anatomic, vol. ii., 1866. 



Fig. 480. 



Fig. 481. 



Fig. 480. VERTICAL SECTION THROUGH THE CJIOROID AND RETINA KEAR THE ORA 

 SERRATA (from Kolliker). f 



a, hyaloid membrane ; of, indications of fibres which radiate from the anterior margin 

 of the retina into the vitreous body ; 6, limiting membrane and fibrous layer of the 

 retina ; c, ganglion! c layer with a few cells shown ; d, inner nuclear layer ; e t inter- 

 nuclear substance ; /, outer nuclear layer ; g, columnar layer ; h, dark pigment ; i, 

 middle layer of the choroid ; I, beginning of one of the ciliary processes ; m, ciliary part 

 of the retina. (The recess shown at a' is not constant.) 



Fig. 481. A SMALL PORTION OF THE CILIARY PART OF THE RETINA (from Kolliker). ^~ 2 - 

 A, human ; B, from the ox j 1, pigment-cells ; 2, cells forming the ciliary part. 



THE VITKEOUS BODY. 



The vitreous body is the largest of the transparent parts occupying the 

 centre of the eye-ball. Globular in form, it occupies about four- fifths of the 

 ball, and supports the delicate retina, being in contact with the membrana 

 limitans. On the fore part it is hollowed out for the reception of the lens 

 and its capsule, and behind it is more closely connected with the retina than 

 at the sides, having received at that part offsets of the retinal vessels in 

 foetal life. It is quite transparent, and like a thin jelly in its interior. Its 

 surface is formed by a thin enveloping glassy membrane, named hyaloid, and 

 as long as this membrane is entire, it retains its form in water. No vessels 

 enter it, and its nutrition must be therefore dependent upon the surrounding 

 vascular textures viz., the retina, and the ciliary processes. 



The hyaloid is an extremely thin and clear membrane. When traced 

 forwards it is found to be connected, opposite the outer part of the ciliary 

 processes, with a firm membrane passing in front of the marginal part of 

 the lens (suspensory ligament), while a thinner layer, proceeding inwards 

 from this, becomes united with the posterior layer of the capsule of the 

 lens, so that it is doubtful whether or not the membrane is prolonged 

 between the capsule and the vitreous body. On the inner surface of the 

 hyaloid are a few delicate nuclei. Fibres have been supposed to be pro- 



