118 



THE DOG IN HEALTH. 



The whole body of an animal must be regarded as a 

 sort of factory, in which numberless chemical processes 



Fig. 4.— Hair and Hair-folliole (after Sappw). 



t, root of hair ; a, 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 bauds passing to skin ; 9, com- 

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

 11, simple sebaceous gland ; 12, opening of hair-folhcle. 



