RESPIRATION AND EXCRETION 



353 



color. On the palms of the hands and soles of the feet 

 the cuticle becomes quite horny in structure. 



The dermis or true skin is largely composed of connective 

 tissue with a mass of blood-vessels, nerves, sweat glands and 



a, 





FIG. 178. Section perpendicularly through skin, a, epidermis; &, pig- 

 mentary layer of epidermis; c, papillary layer of dermis; d, dermis or 

 true skin; e, fatty tissue; /, g, h, sweat glands and duct; /, k, hair 

 with its follicle and papilla; /, sebaceous gland. (After Brubaker.) 



hair follicles. This part of the skin is very sensitive owing 

 to the numerous tactile corpuscles which are the end-organs 

 of the nerves (fig. 183). 



Nails. --The nails are modified epidermal cells. The 

 growing part of the nail is embedded beneath the skin at 

 the base of the nail. The nail protects the ends of the 

 fingers and renders them more useful. 



