THE EYE. 405 



an inch long, though the lower one is rather longer than the 

 upper. 



The lachrymal ducts commence at a small elevation of the 

 margin of each eyelid, bordering immediately upon the internal 

 end of the tarsus cartilage, but perfectly distinct from it. This 

 elevation is conical, has a vermicular motion during life, and 

 points towards the ball of the eye; in its centre is a very small 

 foramen, called the Punctum Lachrymale, which is the begin- 

 ning of the lachrymal duct. The punctum is about a line in 

 length; and enlarging in its course, it runs at right angles to the 

 duct into which it empties, of which it may be called the Orbital 

 Orifice: the upper one will, therefore, ascend, and the lower one 

 descend. 



The lachrymal ducts are much larger than the puncta, and 

 are in their whole course about one line in diameter. At their 

 orbital extremities, they go rather beyond the puncta, so as to 

 form a small cul-de-sac. These canals converge, and having 

 got to the internal angle of the eyelid, they are there placed be- 

 hind the internal palpebral ligament. They then discharge, by 

 distinct orifices, but very near each other, into the lachrymal 

 sac at its external anterior part, where they form a small round 

 projection into the interior of its cavity, and are overlapped, 

 sometimes, by a small duplicature of its lining membrane. 

 When the eyelids are closed, the lachrymal ducts are horizontal 

 and nearly parallel, but when the eye is open the upper duct is 

 elevated, and thereby becomes oblique; it is hence more proper 

 for the introduction of instruments into the lachrymal sac. 



The Lachrymal Caruncle (Caruncula Lachrymalis) is placed 

 in the angle formed by the internal junction of the eyelids. It 

 is a red-coloured tubercle, differing in size in different individu- 

 als, but commonly as large as a grain of wheat It is conical, 

 and obtains its redness from the conjunctiva being reflected over 

 it: when accurately examined, it will be found to consist in a 

 group of sebaceous glands; of which, according to some anato- 

 mists, there are seven ranged two in a row, and one on the top 

 of the others. The surface of this body is beset with very fine 

 hairs, and the orifices in it are distinguishable with a glass. 



The Semilunar Valve, or Fold, (Plica Semilunaris,) is situ- 



