128 SKIN AND ITS APPENDAGES. 



the secreted fluid from the cutis-vera, thrown out, it would 

 seem, like varnish over the whole surface of the body, and 

 then condensing and hardening into the scales just men- 

 tioned. 



The process of formation is thus seen by the microscope. 

 The capillaries of the cutis-vera throw out lymph, contain- 

 ing numerous cell-germs ; these soon enlarge into cells, 

 and closely apply themselves to the surface of the cutis. 

 When this layer is completed a second layer forms beneath, 

 and the first then becomes separated from the true skin, 

 changes its form and consistence, becomes flat and hard, 

 and, by evaporation, dry and firm, and finally falls off in 

 scales ; and this succession of changes, from the primitive 

 secreted nucleus of the cell germ, up to the dry flattened 

 desquamating scale, is continually going on. 



The cuticle is flexible, elastic, and easily torn. Boiling 

 water extracts some gelatine, renders it white, opaque, 

 and deprives it of elasticity. When dry, its volume is di- 

 minished, becomes firmer, slightly yellowish, and resists 

 putrefaction for a long time, Fire causes it to burn like 

 horn and emit a similar odor. The fixed alkalies resolve 

 it into a soapy substance. Nitric acid turns it yellow 

 almost immediately, and thickens, softens and reduces it 

 to a pulp in twenty-four hours. 



The skin thus constituted of the cuticle, rete-mucosum, 

 and cutis-vera, has its external surface moistened by two 

 kinds of fluids the one watery in its nature, called the 

 perspiration the other unctuous in its character, and 

 known as the sebaceous. 



The perspiration, which, when augmented in quantity, 

 becomes the sweat, is furnished by follicles called the sudo- 

 riferous or sweat-glands, (Fig. 19 ;) they are found in all 

 parts of the skin, are of a round form, and consist of a 

 co3ca, ending in a spiral tube, the exhalent duct, which 

 passes through the cutis, rete-mucosum, and cuticle, open- 

 ing on the latter by a minute pore. In the axillae they are 

 described as large, very distinct, and, by their reddish color, 

 readily distinguished from the fatty grains adjoining them. 



