Monthly Mlcroscopican 
Journal, Nov. 1, 1869. J 
Histology of the Eye, 
227 
these spaces occur in the portion enlarged at Fig. 2 h, whicli was 
accurately drawn with the aid of the camera lucida. In the longi- 
tudinal section (Fig. 4), made at right angles to the radius, several 
of these openings are shown. There is an apparent approach at 
regularity in their arrangement, which induces me to suppose that 
they may he the openings through which the vascular bundles 
passed to the leaves. They may, however, be only cracks produced 
in the desiccation of the tissues. 
Beyond this cylinder no structure is preserved, until we reach 
the surface of the stem with the impressions of the leaves and the 
series of larger scars. The parts preserved agree so nearly in re- 
gard to the nature and arrangement of the tissues with what I have 
described in Lepidodendron selaginoides (Sternb.), that there can- 
not be any doubt as to the close affinities of these two stems. The 
structureless space represents the portion occupied with the delicate 
parenchyma, the more thickened and larger parenchyma beyond, 
and the elongated cells of the outer portion, together with the true 
bark. The proportion between the scalariform cylinder and axis 
and the external layers of parenchyma is the same in both stems. 
In the Le^idodendron selaginoides, figured on Plate XXVII. in 
the October number of this Journal, the cylinder measures ith of 
an inch, and the whole stem is an inch in diameter, while in the 
Ulodendron minus, figured on Plate XXXI., the scalariform struc- 
tures are fths of an inch in diameter, and the stem in its original 
cylindrical form measured 4 inches. The proportion of the axis in 
both is ^th of the whole stem. 
II. — The Histology of the Eye. By John Whitaker Hulke, 
F.K.S., F.E.C.S., Assistant-Surgeon to the Middlesex Hospital, 
and Surgeon to the Koyal London Ophthalmic Hospital. 
The eye is a microcosm — a very compendium of all the tissues. 
True cell-tissues, connective tissue in several forms, muscular, 
vascular, and nervous tissue, are all represented here ; and there 
is not another part of the whole human body which offers such 
facilities for direct clinical observation, and for the anatomical 
investigation of the minute tissue-changes produced by disease. 
Cornea. — The cornea is composed of three distinct structures : 
an outer or conjunctival layer, which, at the circumference, passes 
into the loose conjunctiva covering the sclerotic ; a middle layer, 
the proper or lamellated cornea, which is uninterruptedly con- 
tinued into the sclerotic ; and a very delicate inner layer, having 
complex peripheral relations with the sclerotic, ciliary muscle, 
and iris. 
R 2 
