INTEGUMENT OF MAMMALS 



143 



above the pa])illa form the shaft, which, with its dilVerentiating and 

 cornifying cells, is thrust upward into the canal leading through the 

 epidermis. 



Between the hair itself and the follicle wall is a space, and into 

 this, not far from the surface, opens the excretory duct of a sebaceous 



Den 



Sebaceous (jlatul -— 



Cortex of hair 



Vessel 



Dermic coat 



Outer root 



f:^" Stratum corneum 



^~ Stratum lucidutii 

 ^ Stratum granulosa in 

 ' Stratum mucosum 

 " Stratum 



germinatimim 



oj nair - 7-,^:Kr — -^^T" - r --- 'y^ 



uc coat ^-^^^^^^jr^^^^^^ 

 Inner root sheath - V-- —s\^^'^-'<^~rr ^ 



r c^ "r'.^y; Arrector pili 



-~>~''^-'^'-'"~ ' muscle 



Dermic coat 

 Z::^ • Medulla of hair 



Bulb of hair - 

 Papilla of hair — -'^S^S"'^-^..^ — 



Fig. 86. — Diagram of skin structure in region of a hair. (Gray's Anatomy.) 



gland. The epidermis of the follicle, from the surface as far down 

 as the sebaceous gland, has the usual e])idermal layers of the skin; 

 but further down, first the corneum, and then the granular layer, 

 disappears imtil only the Malpighian layer, or stratum germi- 

 nativum, persists in the deeper portion of the follicle. This per- 

 sisting layer thins down to form the external root sheath around 



