158 THE HUMAN BODY. 



lids. According to some anatomists, it is not the conjunctiva, 

 but only an expansion of its epithelium, which covers the 

 cornea. 



Eyelids. An elliptical muscle extends in front of the 

 orbit, which is formed of concentric fascicles, and which 

 presents a transverse chink closed during contraction, and 

 open in the shape of an almond when its fibres are relaxed. 

 This is the orbicular muscle of the eyelids. Its ocular surface 

 is covered by the conjunctiva, its external face by the skin, its 

 opening is circumscribed by the edge of the lids, which are 

 made firm by the tar sal cartilages. The upper lid is larger than 

 the lower, and is raised by a special muscle, the contraction 

 of which alternates with that of the orbicularis, which is its 

 antagonist. The points where the eyelids are united by their 

 commissures are called the angles of the eye. At the internal 

 or greater angle of the eye, the conjunctiva forms a fold, 

 the semi-lunar fold, which is in fact a rudimentary repre- 

 sentative of the third eyelid (membrana nictitans) of certain 

 animals. Inside of this fold is the lachrymal caruncle, a 

 small glandular body of a rose colour, which is covered by 

 the conjunctiva. The edges of the lids are ornamented with 

 a fringe of silky hairs which protect the eye, and add greatly 

 to its beauty. The greater or less extent of the opening of 

 the lids makes the eye appear larger or smaller; the confor- 

 mation of the palpebral muscles and the tarsal cartilages gives 

 to the eye an elongated and languishing form as in the East, 

 or round and bold as among the Occidentals; but the dimen- 

 sions and form of the globe are the same in all countries and 

 in all individuals. 



The upper lid, which is attached to the arch of the orbit, is 

 surmounted by the eyebrow, which is designed to protect the 

 eye like a visor, and its movements play an important part 

 in the expression of the face. 



Lachrymal apparatus. This is composed of, firstly, the 

 lachrymal gland, which lies in a depression of the orbital arch, 

 and of little glands of the same nature, which form a granular 

 layer in the substance of the upper lid; secondly, of the lachry- 

 mal canals, by which the tears are poured out upon the con- , 

 junctiva, a little above the border of the upper lid; thirdly ', 



