MSournal, Ost 1 1810. Crystalline Lens in Man. 223 
of plates. The osseous tissue contains well-developed lacune, and 
where the plates are thick they are hollowed by vascular canals, 
and by medullary spaces enclosing fat-cells. It appears to be 
evolved out of fibrous tissue. 
The cartilage is of the hyaline variety. In the track of the 
sclerotic in many eyes the cartilaginous tissue exceeds the common 
connective tissue. 
The optic nerve pierces the sclerotic a little below and at the 
inner side of the posterior pole of the eye-ball, the nerve appearing 
at its inner surface, nearly 1” to the nasal side of the fovea cen- 
tralis retin, in the form of a disc, usually circular, sometimes 
elliptical, and when so the major axis is generally vertical. 
The common aperture in sclerotic and choroid through which 
the nerve passes is a canal narrower anteriorly, where it lightly 
clasps the nerve, and wider posteriorly, where it loosely embraces 
it. Around this opening the choroid and the sclerotic adhere 
very intimately, their fibrous tissues intermingling here concentri- 
cally around the nerve. 
Here too the minute recurrent branches of the posterior ciliary 
arteries distributed to the outer part of the sclerotic effect a shght 
communication with the capillaries in the nerve-sheaths, and indi- 
rectly with those in the nerve itself. Some of these last inosculate 
with the choroidal blood-vessels in the level of the choroidal open- 
ing. Through these collateral channels, where the trunk of the 
arteria centralis is plugged, a small quantity of blood can enter the 
retina. This choroidal stroma around the nerve contains the same 
stellar pigment-cells which occur in it elsewhere. In some eyes, in 
this situation, these cells are more plentiful and richer in pigment, 
and in such eyes the connective-tissue corpuscles of the neigh- 
bouring sclerotic are also not unfrequently pigmented. This excess 
of pigment expresses itself in the living eye by an incomplete 
narrow brown or blackish ring round the optic nerye-disc. 
In the plane of the choroid and of the inner third of the sclerotic 
- the nerye-opening is crossed by a fibrous web—the lamina cribrosa 
—which peripherally merges in the connective tissues of these two 
coats. The anterior surface of this perforated lamina is concaye, 
the posterior convex. In the living eye the lamina reveals itself as 
a white tendinous spot stippled with minute grey dots, the bundles 
of nerve-fibres going in its meshes. ‘These details are recognizable 
in the healthy nerve-disc in a small central area which corresponds 
to a depression which I shall presently describe, known as the 
physiological pit. A strongly-defined image of these details of the 
lamina overstepping this limit, and reaching towards or even touch- 
ing the edge of the disc, is a sign of atrophy. 
The nerve-fibres in the trunk of the nerve, behind the lamina 
cribrosa, are of the opaque or double-bordered sort, while in front of 
