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



Wiedersheim's Comp. A natomy.) 



Ap, muscles for erecting the hair ; Co. derm ; F . outer longitudinal layer, and F 1. 

 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, ".*., 

 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 eptderm ; Sch. hair-shaft ; S.V. Malpighian layer of epiderm ; 

 W S, WS 1 . external and internal root-sheath. 



485 



