SYSTEMATIC ANALYSIS OF ORGANS. 135 



QUIRES an oily fluid that shall prevent too great evap- 

 oration from the skin (not evaporation of the perspira- 

 tion which flows out of its tubes on to the surface of the 

 oil), and protect it from other external influences. 



513. THE OILY FLUID is of three varieties, the com- 

 mon, the ear-wax, and the viscid fluid of the Meibomian 

 glands that keeps the tear-fluid from pouring over the 

 lids. 



FIG. 114. 



Fig. 114 represents the left eye-lids, cut through as far from their 

 opening as possible, and the Lachrymal Gland drawn from its place, and 

 with the lids turned toward the nose to show the inner surface of the lids, 

 in which the Meibomian Glands, 6, are seen, opening at the edges, between 

 which the lashes are seen. 14, numerous openings of the ducts, 9, 10, 

 from the Gland, 7, 8. 12, 13 are the minute openings at the inner corner 

 of the lids, through which the tear-fluid passes to the nose. 



514. THE SURFACE OF THE AIR AND FOOD PASSAGES 

 requires a slimy but not oily fluid, called mucus, that 

 will not too readily evaporate, and will facilitate the 

 passage of the air and food ; and as the evaporation in 

 the nose and mouth is greater than elsewhere, they 

 should both be still further moistened. 



515. THE LINING OF THE NOSE is kept moist by the 

 mucus, and the tear-fluid that passes into the nose after 

 serving its purpose in the eye. 



518. How class ? Describe Fig. 114. 514. What do ? 515. What said of? 

 What is the quantity of the tear-fluid ? Is it always the same ? 



