STRUCTURE OF THE EPIDERMIS. 



439 



(tenacula cutis) ; in other parts, as over bony prominences, bursa? partially lined with endo- 

 thelium and filled with synovia-like fluid, occur. 



Smooth muscular , fibres occur in the chorium in certain situations on extensor surfaces 



Fig. 294. 



I, Vertical section of the skin, with a hair and sebaceous gland, T. Epidermis and chorium 

 shortened 1, outer ; 2, inner fibrous layer of the hair-follicle ; 3, its hyaline layer ; 4, 

 outer root sheath ; 5, Huxley's layer of the inner root sheath ; 6, Henle's layer of the 

 same ; p, root of the hair, with its papilla ; A, arrector pili muscle ; C, chorium ; a, sub- 

 cutaneous fatty tissue ; b, epidermis (horny layer) ; d, rete Malpighii ; g, blood-vessels of 

 papilla? ; v, lymphatics of the same ; h, horny or corneous substance ; i, medulla or pith ; 

 k, epidermis or cuticle of hair ; K, coil of sweet-gland ; E, epidermal scales (seen from above 

 and en face) from the stratum corneum ; R, prickle cells from the rete Malpighii ; n, super- 

 ficial, and m, deep cells from the nail ; H, hair magnified ; e, cuticle ; c, medulla, with cells ; 

 /, /, fusiform fibrous cells of the substance of the hair ; x, cells of Huxley's layer ; I, those 

 of Henle's layer ; S, transverse section of a sweat-gland from the axilla ; a, smooth muscular 

 fibres surrounding it ; t, cells from a sebaceous gland, some of them containing granules of oil. 



(Neumann) ; nipple, areola mamma?, prepuce, perineum, and in special abundance in the 

 tunica dartos of the scrotum. 



[Guanin in the Skin. The skin of many amphibians and reptiles contains brown or black 

 pigment-granules, and other granules of a white, silvery, or chalky appearance. Ewald and 

 Krukenberg have shown that the latter consists of guanin, and that this substance is very 

 widely diffused in the skin of fishes, amphibians, and reptiles. Test : Select a piece of skin 



