228 



THE FLUIDS. 



Fig. 136. 



Fig. 137. 



Meibomian gland, a. Basement mem- 

 brane. 6. Epithelial cells, c. Duct 



Ceruminous glaud, highly magnified. 1, 1. Tube form- 

 ing the gland. 2. The excretory duct. 3. Vascular trunk 

 and its ramifications. 



Functions. The sebaceous secretion diminishes the tendency to 

 evaporation from the hair and the epidermis; and thus prevents the 

 drying up of the deeper layers of the epidermis, and .consequently 

 of the corium. 



The Meibomian fluid prevents the lachrymal fluid from flowing 

 directly over the lids, from the conjunctiva; and the cerumen both 

 secures a proper moisture of the auditory passage, and, by its nau- 

 seous odor, deters insects from entering it. 



II. PEKSPIKATION. 



True perspiration (sweat) is the fluid secreted by the perspiratory 

 glands, which are situated beneath the skin, in the subcutaneous 

 areolar tissue. They are delicate tubes, forming twisted coils at 

 their commencement, from which they pass in a vertical direction 

 through the corium of the skin, and in a spiral or cork-screw man- 

 ner through the epidermis, to open upon the surface of the latter 

 with a somewhat contracted mouth. Fig. 138 represents one of 

 these glandular coils, with a part of its duct. 



Sweat, as collected on the skin, is a colorless, very watery fluid, 



