Monthly Mlcroscopfcan 
Journal, Nov. 1, 1869. J 
Histology of the Eye, 
235 
first produces, in its most complete form, very finely fibrillated 
tissue. (Fig. 5.) 
Where the fission of the cell-wall is carried to a less degree, it 
produces open fibre cell-nets of coarser texture, which are often 
combined with corrugated hyaloid membranes. 
Proliferation of the nucleus in a minor degree is common in 
association with chronic irritative affections of the vascular coats — 
e. g. chronic glaucoma and the late stages of posterior staphyloma, 
in which we find the cells larger than normal, but still retaining 
Fig. 5. Fig. 6. 
Fibrillation of Cells of Vitreous Humour. Proliferation of Cells of Vitreous Humour. 
their simple forms, and containing two, three, or several nascent 
cells, instead of a single nucleus. But it is in suppuration that pro- 
liferation is carried to its highest development. Advanced cases, 
where the entire corpus vitreum is changed into a tough yellowish 
substance, are not suitable for the demonstration of this ; but, 
before its metamorphosis is complete, at an earlier stage, in which 
the opacity due to the presence of pUs diminishes from the exterior 
towards the still transparent centre of the organ, all the interme- 
diate phases between the simple mononucleated embryonal cell and 
perfect pus are easily traceable. (Fig. 6.) 
The Tunica Uvea, so named from its resemblance to a grape or 
large berry, uva, consists of two segments — the iris and the choroid 
— which differ in their principal anatomical constituents and in 
the offices which they subserve in the physiology of vision, and 
agree mainly in both of them containing numerous blood-vessels 
and much pigment. 
The Choroid corresponds to the coat of lamp-black with which 
we line the interior of the camera obscura, and serves the same 
purpose, absorbing the incident rays, and so lessening dispersion in 
proportion to the intensity of its pigmentation. But, the eye being 
a hving camera, the choroid has additional functions of another kind. 
It directly ministers to the nutrition of the bacillary stratum of the 
retina in man, as also to that of all the retinal strata in those 
animals whose retinae are devoid of blood-vessels. 
