154 SKIN AND ITS APPENDAGES, 



scale-like cells, destitute of nuclei, is exactly similar 

 to the horny surface of the epiderm ; it terminates by 

 growing generally thinner in the upper third of the 

 follicle, about where the excretory duct of the seba- 

 ceous glands appended to the hair pours out its secre- 

 tion (PI. XXIV, fig. IV. 10; PL XXV. fig. II. 5) ; 

 P. XXVII. fig. V. 3). A very small fasciculus of 

 unstriped muscular fibres is attached to the bottom 

 of the hair follicle externally, on the side towards 

 which the hair inclines ; it passes obliquely upwards 

 to the surface of the true skin, where it is inserted ; 

 this is the muscle, by the contraction of which the 

 hair is made to straighten up at right angles to the 

 surface of the skin, or, as the phrase is, to " stand on 

 end." 



The papilla which occupies the excavation at the 

 bottom of the bulb belongs to the true skin, and is 

 more delicate in its structure than its other papillae. 

 It contains several vessels which form loops in its 

 interior, but its connexion with the nervous system is 

 as yet unknown (PL XXV. fig. II. 7). 



Development. The hair and the two epidermic layers of its fol- 

 licle, are developed from a minute mass, or granula- 

 tion of the rete mucosum which imbeds itself in the 

 surface of the cutis, whilst the two outer strata of the 

 walls of the follicle are derived from the formative 

 cells of the true skin. The hair is developed all in 

 one mass, from the little germ at the bottom of its 

 follicle ; the cells composing which, by their various 

 transformations, produce the several elements of 

 which it consists, as well as the two epidermic layers 

 by which the follicle itself is lined. 



