FIG. 131. Longitudinal section through a hair-sac. (Diagrammatic.) (From 



Wiedersheim's Comp. Anatomy.') 



Ap. muscles for erecting the hair ; Co. derm ; F. outer longitudinal layer, and F^. 

 inner transverse layer of connective-tissue fibres of hair-sac ; Ft. adipose tissue ; 

 GH. hyaline layer, which lies between the inner and outer hair-sheaths, i.e., 

 between the root-sheath and the hair-sac ; HBD. sebaceous glands ; HP. hair- 

 papilla, containing vessels; M. medulla; O. cuticle of shaft; R. cortex; Sc. 

 horny layer of epiderm ; Sch. hair-shaft ; SM. Malpigian layer of epiderm ; WS, 

 IPS*, external and internal root-sheath. 



