*j?uSL. jJSyTiff ] ^^^^^ Human Vitreous Humour. 31 
of strong, smooth fibres, not unlike the fibres of common fibrous 
tissue, which form a coarse, open web, in the large meshes of 
which the finer network of anastomosing cells is woven (Fig. lb). 
These fibres are evidently for the purpose of giving strength to 
the humour in these situations. 
The tissue of the vitreous body is entirely composed of an open 
meshwork, and nothing in the shape of membranes can be seen in 
it with the microscope. But the microscopic examination of the 
vitreous humour in detached portions can convey no idea of the 
design of its structure as a whole; and contrary, therefore, to 
what might be anticipated from microscopic observation, the strong 
fibrous tissue, which exists only towards the circumference of the 
vitreous body, is discovered by the naked eye to be woven into 
membranes or membranous strata, having a determinate direction 
within the humour, while the anastomosing cellular tissue, on the 
other hand, occupies the intermembranous spaces in the manner 
of loose connective tissue. 
To demonstrate these membranes and the intermembranous 
tissue in their relative situations, it is necessary to have recourse 
to another method than that already described, for the purpose of 
rendering the parts opaque as a whole, in order that they may be 
seen in situ with the naked eye. Of the methods which may be 
employed for this purpose, the one most conclusive and least likely 
to embarrass the observer is that which allows the tissue to become 
opaque from age, a small quantity of preservative fluid being used 
merely to prevent it undergoing the process of putrefaction. To 
accompKsh this, the eyeball should be allowed to stand four or five 
days in water, when it is to be divested of its tunics, and the vitre- 
ous body, with the crystalline lens and capsule, entire, placed in a 
solution of carbolic acid, of about the strength of one of the latter 
to three hundred of water. At this stage the vitreous humour is 
of a straw-yellow or greenish colour, owing to the infiltration into 
it of the colouring matter of the blood, which somewhat masks the 
view of the fabric within; but in a few days the sanguineous 
colouring matter is disseminated into the surrounding menstruum, 
leaving the structure of the humour quite apparent to the naked 
eye. 
A vitreous body, having been prepared according to the pre- 
ceding directions, is to be placed in a wine-glass, or other ehgible 
clear glass vessel, covered with water, and examined with the naked 
eye as the direct rays of the sun are condensed upon it by means 
of a convex lens. When so examined, the structures within the 
humour will be found to have the following arrangement : — 
(a) Passing through the vitreous body from the point where 
the optic nerve pierces the eyeball to the posterior capsule of the 
crystalHne lens, but inferiorly and internally to the axis of vision. 
