THE SPECIAL SENSES AND SENSATIONS 



269 



hairs on the edge of each lid. The hairs have delicate 

 nerves at their roots and so serve to warn us against 



fyeiasties 



Sc/erof/c 



FIG. 143. The left eye (Zinns). 



small objects approaching the eye and against dust. 

 The eyebrows protect the eye against dust and perspira- 

 tion, and they give it shade. 



The tear glands (lachrymal glands) are situated 

 above and at the outer angle of the eye. They secrete 

 the tears and pour them 

 out under the upper lid, 

 where they are distrib- 

 uted over the eye so as 

 to moisten the entire 

 cornea. Each lid has a 

 small duct at its inner 

 end, into which the 



moisture is Collected FIG. 144.- The lachrymal apparatus 

 - ... .. , , (Zuppke). 



after it has accomplished 



its purpose. These two ducts unite and lead to the tear 



bag (lachrymal sac), from which a single duct leads to 



Uucfc 



