GLANDS OF THE EYE 



289 



junctival sac, where it would accumulate were it not for the fact 

 that the movement of the lids drives it towards the anterior (inner) 

 angle of the eye, where the puncta lacrymalia are situated, often on 

 small papillae. These lead into short ducts communicating with 

 the so-called lacrymal sac which opens into the naso-lacrymal duct. 

 A well-differentiated Harderian gland, sometimes consisting of 



lit 



FIG. 210. A. HARDERIAN GLAND (ff, H l ) AND LACRYMAL GLAND (Th) OF 



Anguis fragilis. 



B, eyeball ; M , muscle of jaw. 



FIG. 210. B. DIAGRAMMATIC TRANSVERSE VERTICAL SECTION TBBOUGH THE 

 EYE OF A MAMMAL. 



B, eyeball ; Fo, Fo, upper and lower con junctival sac ; H, If, eyelashes ; LH, 

 ~LH, outer skin of the eyelids, which at the free edges of the latter, at t> 

 becomes continuous with the conjunctiva ; Op, optic nerve ; T, the so-called 

 tarsal fibro-cartilages, in which the Meibomian glands (MD) lie embedded, 

 the latter opening at *. 



FIG. 210. C. DIAGRAM OF THE LACRYMAL APPARATUS OF MAN. 



/), naso-lacrymal duct ; S, lacrymal sac ; TD, lacrymal gland, divided up into 

 several portions; TR, TK 1 , upper and lower lacrymal canals; *", ducts of 

 the lacrymal gland ; ft. puncta lacrymalia. 



histologically and physiologically different elements, is present 

 from the tailless Amphibia to the Mammalia, but is rudimentary 

 in the Primates. 



TheMeibomian glands (Fig. 210, B) are confined to the Mammalia, 

 and lie embedded in the substance of the eyelids in the form of 

 branched, tree-like tubes or clustered masses. They open on the 

 free edge of the lid, produce a fatty secretion, and originally 



