118 



THE DOG IN HEALTH. 



The whole body of an animal must be regarded as a 

 sort of factory, in which numberless chemical processes 



Fia. 4. HAIR AND HAIR-FOLLICLE (AFTER SAPPEY). 



1, root of hair ; 2, bulb of hair ; 3, internal root-sheath ; 4, external root-sheath ; 

 5, membrane of hair-follicle ; 6, external membrane of follicle ; 7, 7, muscular 

 bands attached to follicle ; 8, 8, extremities of bands passing to skin ; 9, com- 

 pound sebaceous gland, with duct (10) opening into upper third of follicle ; 

 Jl, simple sebaceous gland ; 12, opening of hair-follicle. 



