236 ANATOMY FOR NURSES. [CHAP. XIX 



the lachrymal sac, which is the upper dilated portion of the nasal 

 duct. 



The nasal duct is a membranous canal, about three-quarters 

 of an inch in length, which extends from the lachrymal sac to 

 the inferior meatus of the nose, into which it opens by a slightly 

 expanded orifice. 



The tears consist of water containing a little salt and albu- 

 min. They are ordinarily carried away as fast as formed, but 

 under certain circumstances, as when the conjunctiva is irri- 

 tated, or when painful emotions arise in the mind, the secretion 

 of the lachrymal gland exceeds the drainage power of the nasal 

 duct, and the fluid, accumulating between the lids, at length 

 overflows, and runs down the cheeks. 



