456 



CHORD AT A. 



forms the outer root-sheath ; the mucous layer inside it is 

 known as the inner root-sheath and upon its surface is pro- 

 duced the sheath-cuticle. In a similar manner the hair 

 itself has a central medulla produced from the basal 

 epithelium, a cortex around it, formed by the mucous layer, 



Fig. 321. — Diagrammatic Sections Illustrating the 

 Development of a Hair. 



C D 



A, The hair-germ. B, Formation of papilla and axis. C, Formation of cuiicular 



cylinder. D, Splitting of cuticular c^'^linder and formation of hair. 



E, Transverse section of D. 



and outside this a thin hair-cuticle. The cortex becomes 

 eventually transformed into ceratin and usually carries the 

 pigments which give hairs their peculiar coloration, whilst 

 the medulla becomes a spongy network of cells which often 



