THE SKIN 



233 



Nails. The finger and toe nails are especially thickened 

 parts of the epidermis. Figure 115 represents a lengthwise 

 section through the tip of the finger, showing a nail. It 

 grows chiefly at its base, called the root, and as it grows 

 its free end is pushed out farther and farther. It also 

 grows thick by additions to its un- 

 der surface. The reason why a nail 

 appears whiter at its basal end is 

 that blood capillaries are less plentiful 

 in that region than elsewhere; this 

 "white" of the nail is technically 

 called the lunula. 



THE DERMIS 



FIG. 115. SECTION 

 THROUGH THE END OP 



A FINGER 



Showing the relation of 



the nail to other parts. 



Below the epidermis is a live layer 

 composed of connective tissue, nerves, 

 blood vessels and fat. It is largely 

 made of a dense mass of connective 



tissue fibres like the material we have already noticed 

 in tendons and ligaments, except that in skin it is arranged 

 in a much looser mass; the fibres run in every direction, are 

 closely packed together near the epidermis, but below, near 

 the muscles, become quite loose; Fig. 114. In the spaces 

 between the fibres are masses of fat cells which fill out 

 the skin and make the body appear rounded. If these layers 

 of fat were not there, the skin would cling tightly to the 

 flesh so that muscles and tendons would show through it. 

 When a person is insufficiently nourished, as for example after 

 a long illness, the location of the separate muscles beneath 

 the skin is plainly seen because the fat stored in the dermis 

 has been used. 



The dermis is full of blood vessels. This is most evident on 

 certain areas, e.g. the lips and inner surfaces of the eyelids, 

 where the epidermis is very thin and the capillaries of the 

 dermis show through, giving these areas their red appearance. 



