606 THE EYE 



and the lumen of the acinus is very small. After a period of exces- 

 sive activity the secreting cells become shrunken and more dis- 

 tinctly granular, and the lumen of the acinus appears much dilated. 



The secreting acini empty into narrow intercalated ducts which 

 lie within the lobule, have a considerable lumen, and are lined by 

 tall columnar cells resting upon a second incomplete layer of small, 

 somewhat flattened basket cells. 



These intralobular ducts unite at the margin of the lobule to 

 form the larger interlobular ducts, which are contained in the 

 interlobular connective tissue. Here the duct is lined by low 

 columnar or even somewhat flattened cells, at first disposed in a 

 single, but later in a double layer. As the duct approaches the 

 conjunctival surface the number-of cell layers increases until their 

 lining epithelium finally comes to resemble the stratified epithe- 

 lium of the conjunctiva with which it is continuous. 



Minute collections of diffuse lyrnphoid tissue and even small 

 lymphatic nodules are occasionally found just beneath the epi- 

 thelium of the conjunctiva in the neighborhood of the lachrymal 

 glands of the fornix ; occasionally the lymphoid tissue is quite 

 abundant. 



In mammals possessing a membrana nictitans (" third lid") a 

 small, mucus secreting gland occurs at the inner angle of the orbit ; 

 this is known as the gland of Harder. In man it is usually absent, 

 though in an extremely vestigial condition it may occasionally be 

 found. 



