INTEGUMENT 25 



to the greater or less accumulation of pigment in the cells of the 

 cortical layer ; secondly, to the air contained in the intercellular 



FIG. 16, A. LONGITUDINAL SECTION THROUGH A HAIR. (Diagrammatic.) 



Sc, stratum corneum ; SM, stratum Malpighii ; Co, dermis ; Ap, arrectores pili ; 

 Ft, adipose tissue ; F, outer longitudinal layer, and F 1 , inner transverse layer 

 of dermic coat (both composed of connective-tissue) ; Sch, hair-shaft ; J/, 

 medulla ; R, cortex ; 0, cuticle of shaft ; WS, WS\ external and internal 

 root-sheath, the latter reaches above only as far as the point of entrance of 

 the ducts of the sebaceous glands (HBD) ; HP, hair-papilla, containing 

 vessels ; GH, hyaline layer, which lies between the inner and outer hair- 

 sheaths, i.e., between the root-sheath and the follicle (dermic coat). 



spaces of the medulla ; and lastly, to the nature of the surface of 

 the hair, i.e., whether it is rough or smooth. The hairs are usually 

 arranged in groups of finer and coarser elements, and, especially 

 in the case of the vibrissae, are well innervated. 



