tHE fcALL OF fHE EVE* 427 



the iris, tlie whole of the space posterior to the latter. It is, 

 therefore, very nearly globular; is in contact the greater part 

 of its extent with the retina, at least as far as the latter mem- 

 brane proceeds; in front it is in contact with the crystalline 

 humour, and from the margin of the retina to the circumference 

 of the lens it is in contact with the ciliary body, meaning there- 

 by the ciliary striae and processes of the choroides. 



Two parts compose the vitreous humour, the hyaloid mem- 

 brane and a thin fluid. In a natural state they are perfectly 

 transparent, and, therefore, cannot be readily distinguished 

 from each other; but by immersion in spirits of wine the mem- 

 branous portion is brought to the colour of ground glass, and 

 may then be studied very advantageously. The membrane, 

 though extremely delicate, is generally strong enough to permit 

 the whole vitreous body to be suspended in the air bv a thread 

 passed through it, and it may also be momentarily held up with 

 a pair of forceps.* 



The Tunica Hyaloidea may be traced as a complete capsule, 

 forming the periphery of the vitreous humour; and from the 

 internal face of this capsule there proceeds a great number of 

 partitions dividing the whole cavity into cells of various mag- 

 nitudes and forms. Some anatomists, who have frozen the eye, 

 and then picked out the pieces of ice from the cells, have got 

 the idea ot their being all cuneiform, and of their edges pointing 

 forwards. Our preparations in the anatomical cabinet are per- 

 fectly satisfactory in exhibiting the existence of an arrange- 

 ment of cells, but do not manifest a regular cuneiform shape in 

 them. 



When the capsule of the tunica hyaloidea has got to the dis- 

 tance of two lines, or thereabouts, from the circumference of 

 the lens, it divides into two laminae, which reunite at the cir- 

 cumference of the lens. They then divide again, and one goes 

 before the capsule of the lens, and the other behind it. The 

 space between the two layers, around the circumference of the 



* In Williams the murderer, executed here, as stated before, I found on the 

 front of one hyaloid, just at the side of the lens an opacity of three by six lines, 

 resembling an opacity of the cornea, it was just where the tunica hyaioidta is in 

 contact with the ciliary plaits of the choroid and was first mistaken tor a metallic 

 like surface of the lather, as. the tapetum of the lower animals. 



