808 



THE SENSE OF SIGHT 



tiva. Eventually it is collected in the lacrimal lake, a bay-like ex- 

 pansion at the inner angle of the eye overlying the plica semilunaris 

 and the spongy reddish elevation, known as the caruncula lacrymalis. 1 

 We observe here that each lid is slightly raised into a papilla, the 



FIG. 421. DIAGRAMMATIC REPRESENTATION OF ALVEOLI OF THE LACHIMAL GLAND. 

 A, during rest; B, after activity produced by pilocarpin. 



apex of which displays the orifice (punctum) of a small canal, known 

 as the canaliculus lacrymalis. The purpose of these tubules is to 

 convey the tears out of the conjunctival sac into the lacrimal sac, 

 representing the slightly dilated orbital end of the lacrimal duct. 



LcuihrtnnaZ canals JFi 



FZ 



FIG. 422. SECTION SHOWING THE COURSE AND RELATIONS OF THE NASAL SAC AND DUCT. 

 (Slightly modified from Merkel.) 



The latter is about 5 mm. wide and 15 mm. long, and continues on- 

 ward in the form of the nasal duct which finally terminates in the 

 fore-part of the lower meatus of the nose about 30 to 35 mm. behind 

 the posterior margin of the anterior nasal opening (Fig. 422). 



1 Stieda, Archiv fur mikr. Anatomic, xxxvi, 1890. 



