320 



TEE HUMAN 



continual presence makes itself unpleasantly felt, and 

 may need the aid of a surgeon to clear the passage. In 

 weeping the secretion is increased, and then not only more 

 of it enters the nose, but some flows down the cheeks. 

 The frequent swallowing movements of a crying child, 

 sometimes spoken of as " gulping down his passion," are 

 due to the need of swallowing the extra tears which reach 

 the pharynx. 



FIG. 88. The left eyeball in horizontal section from before back. 1, scle- 

 rotic; 2, junction of sclerotic and cornea; 3, cornea; 4, 5, conjunctiva; 6, pos- 

 terior elastic layer of cornea; 7, ciliary muscle; 1C, choroid; 11, 13, ciliary pro- 

 cesses; 14, iris; 15, retina; 1(5, optic nerve; 17, artery entering retina in optic 

 nerve; 18, fovea centralis; 19, region wheie sensory part of retina ends: 22, 

 suspensory ligament; 23 is placed in the canal of Petit, and the line from 25 

 points to it; 24, the anterior part of the hyaloid membrane; 26, 27, 28, are placed 

 on the lens; 28 points to the line of attachment around it of the suspensory liga- 

 mnnt; 29, vitreous humor; 30, anterior chamber of aqueous humor; 31, poste- 

 rior chamber of aqueous humor. 



Why do tears run down the face during a fit of weeping? 



Why does a crying child make frequent swallowing movements? 



