164 ANTHROPOLOGY. 
lid along the ocular surface of the cartilage, and covered by the mucous 
membrane ; their openings are seen with a lens as a row of minute pores 
behind the cilia. They secrete an unctuous fluid which lubricates the 
edges of the lids and the cilia, prevents their friction and adhesion when 
closed, and hinders the overflow of tears when these are secreted in mode- 
rate quantity. ‘ 7 
The conjunctiva, or internal integument of the palpebre, lines these cur- 
tains, and connects them with the eye. At the free edge of each lid, it is 
continuous with the skin. Within the superior lid it ascends, and rises 
above the cartilage into a cul de sac, the superior palpebral sinus, which is 
loosely connected with the cellular and adipose tissue within the orbit, and 
is then reflected on the fore part of the sclerotic coat of the eye. It is 
continued over the cornea as an exceedingly delicate membrane, only sepa- 
rable by previous maceration. From the lower part of the sclerotic, the 
conjunctiva is reflected on the inner surface of the lower lid, forming the 
inferior palpebral sinus, and extends to the margin. At the inner canthus 
of the eye, it forms a vertical fold, the plica semilunaris. The caruncula 
lachrymalis is a small irregular eminence, placed in the lacus, at the inner 
canthus of the internal palpebral fissure, internal to the plica semilunaris. 
It contains a number of minute follicles, which secrete a sebaceous substance 
which often accumulates in the cornea. | 
3. Lacurymau Apparatus. This consists of the lachrymal gland and its 
excretory ducts, the two puncta lachrymalia, the lachrymal canals leading 
from each into the lachrymal sac, and lastly the nasal duct, leading trom 
the latter into the nose. 
The lachrymal gland is of a pale reddish color, surrounded by a cellular 
capsule, situated at the upper and outer aspect of the globe of the eye, a 
position from which its secretion can most effectually flow over the anterior 
surface of the globe. It consists of two lobes, a superior or orbital and an 
inferior or palpebral. Six or eight delicate ducts descend nearly parallel 
from the gland, and open opposite to its lower border by separate orifices 
on the inner surface of the upper lid, commencing about half an inch from 
the outer canthus, and a little above the upper margin of the cartilage. 
This organ secretes the tears which serve to lubricate the eye-ball, and to 
dilute the more viscid secretion of the mucous membrane. The lachrymal 
secretion consists of water, and about one per cent. of chloride of sodium 
(common salt), with a yellow extractive matter. 
The puncta lachrymalia are the two small holes in the cartilaginous 
projections named lachrymal papilla. They are always open and visible to 
the naked eye, at the inner extremity of the ciliary margin of each carti- 
lage, and about two lines distant from the inner canthus. Each opening 
will admit a bristle. They are separated by the caruncula, and each leads 
into the following. | 
The lachrymul canals are two, a superior and an inferior. The superior 
ascends from the punctum, then bends downwards to the anterior and 
outer side of the sac. The lower canal just descends, then ascends and 
opens into the sac very near to the first. 
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