222 The Ciliary Muscle and ae Oa Lene 
vascular papilla. The epithelium consists of several layers of cells, 
the deepest of which are oblong and stand vertically, while the more 
superficial ones are flattened and obliquely packed. The meshes of 
the areolar tissue often enclose large numbers of lymphoid cor- 
puscles. The blood-vessels and nerves are numerous. The nerves 
are remarkable for the specialized terminations some of the tubules 
exhibit—the terminal clubs, end-kolben of Krause. The loose fold 
of conjunctiva which connects the eye-lids and eye-ball, and also the 
palpebral front, but more particularly the former, contain small 
glandiform bodies—minute spherical capsules enclosed in a net of 
capillary blood-vessels, and according to some observers also sur- 
rounded by lymphatics. These when enlarged form the transparent 
bead-like grains which characterize a kind of granular ophthalmia, 
fortunately for us much less frequent in Great Britain than the 
papillose form of this complaint. 
The sclerotic in conjunction with the cornea forms the strong 
outer case of the eye-ball which supports and protects the delicate 
inner coats. It is thickest behind around the optic nerve, becomes 
thinner from the iris to the attachment of the tendons of the mus- 
cular web, in front of which its thickness again increases slightly. 
A funnel-shaped canal pierces it behind for the passage of the optic 
nerve, and it is perforated by many smaller apertures for the 
transmission of the blood-vessels and of the ciliary nerves. Of these 
minor openings the only ones which require notice are those by 
which the venz vorticosz choroid leave the eye-lid. These pierce 
the sclerotic obliquely, which renders them valvular, a mechanism 
that lessens the available opening whenever the pressure on the 
internal surface of the sclerotic rises unduly, and proportionately 
os the egress of the venous blood and raises the pressure still 
igher. 
The sclerotic is principally composed of white fibrous or com- 
mon connective tissue, in the form of flat fibrillated bundles closely 
interwoven in planes, which cross one another at every possible 
angle, but which have a general direction parallel to the surfaces of 
the coat. Amongst the fibrillated tissue are imbedded simple fusiform 
and branched corpuscles, which are more numerous in young than 
in fully-grown persons. ‘The blood-vessels of the sclerotic are not 
very numerous; the most important ones are, as Leben has pointed 
out, the recurrent branches of the posterior ciliary arteries, which 
unite in a small circle which communicates with the vessels of the 
optic nerve. It is yet uncertain whether the sclerotic has any 
nerves distributed to it, the ciliary nerves all appear to pass through 
the coat, and not to furnish branches within their canals. 
In birds, lizards, and turtles the fibrous sclerotic is strength- 
ened by the addition of bone and cartilage. The bone is chiefly 
present in the ciliary region, where it forms the well-known circle 
