228 
Histology of the Eye, 
[Monthly Microscopical 
Journal, Nov. 1, 1869. 
The conjunctival layer consists of an epithelium, underlaid by a 
homogeneous stratum, known as " Bowman's membrane," or the 
" anterior elastic lamina." 
The e;pithelium is composed of four or five superposed rows of 
cells, the aggregate thickness of which averages ^i oth of an inch. 
The deepest cells are subcolumnar. Their inner ends are straight, 
and they rest directly on Bowman's membrane. Their outer ends 
are convex ; and they form generally a crenated line, which inter- 
locks with the cells immediately external to it. These intermediate 
cells have a jagged inner border, and a convex outer contour. The 
outermost cells are large flat scales. 
The structural and chemical distinctions which so sharply 
separate the horny from the mucous stratum of the epidermis are 
wholly absent from this epithelium, all the cells of which, the 
outermost as also the deepest, are nucleated, and are capable of 
manifesting every endowment of cell-life proper to them ; and this 
alone would be enough to throw great doubt on the commonly 
assumed parallelism between the manner of the renewal of the 
corneal epithelium and that of the epidermis. The common idea, 
that the deepest epithelial cells constitute a sort of matrix, from 
which there is a constant progression of nascent cells towards the 
outer surface to replace the loss by exfoliation, has been lately 
challenged by Dr. Cleland, who, from a study of the corneal epi- 
thelium in the ox, concludes that not merely the external waste, 
but also the internal decay of the deepest cells, is made good by 
new cells evolved out of those of the middle tier. My own ob- 
servations lead me to beheve that an outward progression of cells 
from the innermost tier really does take place, but that all the 
superficial cells are not directly referable to this source, since 
proofs of cell-multiplication are met with at every depth in the 
epitheUum. 
But the formative energy may take another direction, and 
produce from the epithelium a progeny unlike the parent. Wounds 
and ulcers, again, afford us abundant illustrations of this perversion. 
Around these we find the epithelial cells enlarging ; their nuclei, 
or masses of germinal matter, dividing and subdividing until the 
parent cell is filled with a brood which we cannot optically dis- 
tinguish from the corpuscles of granulation, or lymph, or pus, and 
which, when set free by the deliquescence of the parent capsule, we 
recognize as the formed elementary constituents of granulation- 
tissue, of lymph, or of pus. (Fig. 1.) 
Bowman s Memhrane : Anterior Elastic Lamina. — Beneath 
the anterior epithelium, between it and the lamellated cornea, 
is the structureless stratum first particularly described by Mr. 
Bowman, and named by him the anterior elastic lamina. In 
several early human foetal eyes I found that this stratum was 
