THE SKIN AND THE KIDNEYS 187 



253. The True Skin. The true skin, or dermis, is a firm, 

 elastic structure resting on meshes of a tissue something 

 like damp, raw cotton, which loosely fasten the skin to the 

 parts beneath. It is the true skin which, in the lower ani- 

 mals, is made into leather by the process of 



tanning. In this layer also are the nerves, 

 blood vessels, and absorbents of the skin. 



When the true skin is destroyed, a scar 

 results. White scars, especially on the 

 hands, due to deep cuts, and scars from 

 smallpox, deep burns, and other injuries 

 to this layer of the skin, are often seen. 



The true skin is richly supplied with 

 nerves and blood vessels so closely netted FIG. 115. Epidermis 

 together that it is next to impossible to from the Bottom of 

 prick the skin anywhere with the point 

 of a needle without drawing blood and feeling pain. 



Experiment 58. Stretch the thumb and forefinger of the left hand 

 wide apart. Gently prick the skin with the point of a fine, clean 

 needle. Note how sensitive the true skin is, and how readily a drop 

 of blood may flow. 



Experiment 59. Press the thumb of the right hand tightly into 

 the left palm. Remove the thumb quickly. Note the difference in 

 color of the spot pressed and that of the skin near by. 



254. The Skin and the Sense of Touch. The outer sur- 

 face of the true skin rises up into the epidermis so as to 

 form little hillocks, or papillae, into which run the capillaries 

 and the nerves. 



In the papillae are little round or oval bodies, called 

 touch corpuscles (Sec. 340). 



These papillae are very numerous everywhere, but are 

 thickest where the sense of touch is most acute, as on 



