402 EYELASHES. LACRYMAL GLANDS. 



it prevents the eyelids from adhering to each other, in conse- 

 quence of their contact during sleep. 



The orifices of these glands, are very minute, but will 

 admit of the introduction of fine bristles. They are disposed 

 in one or two ranges, immediately behind the eyelashes, and 

 presenting toward the ball. These orifices lead into the 

 little lines or ducts, which Meibomius described as glands. 

 But the gland of Meibomius* is now known to be a compound 

 follicle, or rather a series of minute glands ranged parallel with 

 each other upon the sides of the duct into which they open ; 

 some of which communicate together by lateral openings. 

 The oily matter which they deposit on the edges of the lids, 

 serves, in the ordinary state of the eye, to confine the tears, as 

 water is known not to pass so readily over a vessel, the margin 

 of which is greased. 



The eyelashes or cilia are placed near the outer edge of the 

 lower part of the cartilages of each eyelid. They are always 

 more or less curved, and their convexities are opposed to each 

 other. By this arrangement the eye is defended from small ex- 

 ternal objects, and from light to a certain degree, without closing 

 the lid completely. 



The cilia consists of three or four ranges of hairs irregu- 

 larly placed, the middle of which are longest, and which gives 

 to the brush of hairs, a penicillous arrangement. They are 

 strongest and most numerous in the upper lid. Their bulbs or 

 follicles are placed between the skin and tarsal cartilages ;* and 

 of course are not met with in the internal canthus. The lashes, 

 or cilia are covered by an oily fluid, secreted by a number of 

 minute cuticular follicles, common round the roots of all hairs. 

 This secretion tends to keep the hairs separate, and prevents 

 that agglutination that would otherwise take place, from the dry- 

 ing of the lachrymal fluid, mixed as it is with the Meibomian 

 secretion. 



It is necessary, for the perfection of the eye, that the whole 



* The tarsal cartilages thus intervene between the bulbs of the cilia and the 

 Meibomian glands. And upon this is founded Berlinghieri's operation for the 

 cure of Trichiasis, by the extirpation of the bulbs of the glands. p. 



