234 
Histology of the Eye. 
TMonthly Microscopical 
L Journal, Nov. 1, 1869. 
mingled with the fibres, give, under a moderate enlargement (a 
quarter of an inch) some resemblance to a stellar tissue. This 
resemblance is, however, only superficial, and disappears under a 
higher magnifying power which makes it evident that the bright 
globules have not any definite relations to the fibres, since some of 
them lie free in the meshes of the web, and others cohere singly or 
in groups to the sides of the fibres or 
at their intersections. Examined with 
one-twelfth or one-twenty-fifth objec- 
tive, these bright globules do not exhibit 
any trace of structure ; and I am dis- 
posed to conjecture that they are arti- 
ficial products, resulting from the action 
of the chromic acid on the interstitial 
albuminous substance. (Fig. 4.) 
But, besides the formed elements 
just described, there occur in the foetal 
corpus vitreum other elementary ^arfs 
Foetal Vitreous Humour. of the Mghest ]physiological importance 
— large nucleated cells, which are most 
abundant upon and near the hyaloid capsule and around the central 
canal, but which are also found throughout the whole organ. Most 
of them have a simple round or roundly oval shape; some are 
fusiform and branched. All are distinctly nucleated. Their 
diameter ranges between ^Acyth and ^^oth of an inch. 
In the human adult's vitreous body, the foetal fibrillary net steps 
into the background ; but it does not wholly disappear, for portions 
of it persist even to old age ; and it is replaced by delicate mem- 
branes of such extreme tenuity, and difiering so little in their re- 
fraction from that of the fluid substance of the organ, that they 
would elude detection, but for the presence of folds and the adhesion 
of minute impurities to them. The arrangement of these mem- 
branes is not yet certainly known ; and, in truth, their very existence 
is doubted by some anatomists. 
Beyond all doubt, the most important constituents in the 
adult's corpus vitreum are the large nucleated cells which I men- 
tioned as occurring in the foetus. These embryonal cells persist 
throughout hfe, and they are the starting-point of many of the 
morbid changes to which this organ is subject. 
They are endowed with an extraordinary formative energy, 
normally latent, but promptly responsive to an appropriate stimulus, 
the nature of which determines the dynamical direction this energy 
takes. Anatomically, this excessive formative energy principally 
manifests itself in two ways — one marked by a remarkable exten- 
sion and fission of the cell-wall and contained protoplasm; the 
other characterized by inordinate proliferation of the nucleus. The 
