MICROSCOPIC ANATOMY o/ THE OEGAXS. 



glands), which are distributed throughout 

 its whole height. They are alveolar glands, through the 

 entire length of which there is seen a duct lined with stratified 

 fiat epithelium. The ducts open out at the border of the lid, 

 as shown in Fig. 268. Opening into all sides of the duct 

 there are round alveoli. Their cells undergo fatty change 

 and give out a fat-containing secretion. The finer structure 

 of these glands is like that of sebaceous glands. 



At the upper border of the tarsus, in the lateral half of the 

 eyelid, there are, especially in the upper lid, branched tubular 

 glands (Krause's glands), which are to be considered as ac- 

 cessory tear glands. The ducts pierce the conjunctiva and 

 open into the conjunct! val sac. 



The conjunctiva borders directly on the tarsus. It consists, 

 like other mucous membranes, of epithelium and a tunica 

 propria. The epithelium is made up of two or three layers 

 of cylindrical epithelium with a cuticular border on the free 

 sin-face. Among these cells there are vesicular cells contain- 

 ing mucous material. These differ from ordinary goblet cells, 

 in not lying altogether on the surface. According to Pfitzner, 

 they represent the so-called Ley dig's cells, such as are found 

 in the epidermis of the larvae of fishes and amphibians. At 

 the posterior edge of the lid this epithelium passes over into 

 stratified pavement epithelium. Only in the upper part 

 is the conjunctiva not smooth. Here it forms small furrows 

 and folds. The connective-tissue tunica propria contains plasma 

 cells and leucocytes in varying quantity. 



The conjunctiva palpebralis passes over onto the eyeball 

 at the fornix conjunctivas and becomes the conjunctiva sclerce. 

 In the fornix there often occur many small lymph nodules. 

 The epithelium of the fornix and conjunctiva sclerse is similar 

 to that of the cojunctiva palpebralis. The epithelium of the 

 scleral conjunctiva passes over into stratified pavement epi- 

 thelium in the neighborhood of the corneal border. 



The plica semilunarix, which represents the rudimentary 

 third eyelid, consists of connective tissue and stratified pave- 

 ment epithelium. If it is strongly developed, it may contain 



