24 COiiPARATIVE AXATOMY 



medulla, cortex, and cuticle (Fig. 16 A), all of which are formed 

 from cells. The follicular tissue, which is richly provided with 

 blood-vessels, extends into the bulb-like base or root of the hair- 



A /^/' 



Fig. 1.5. — Diagrams ov Four Stages (A-D) in thk Development of HAm--^. 



(After F. Maurer.) 



,Sr, stratum corneiim ; S^f, stratum Malpighii, which gives rise to an epithelial 

 knob at Ep ; this grows inwards into the dermis (C) ; F, rudiment of the hair- 

 follicle ; HP, hair-papilla ; UK, hair-bulb ; Dr, rudiment of the sebaceous 

 gland. In 1), / indicates the stratum lucidum with eleidin-granules in the 

 cells. 



shaft, and gives rise to the huir-i)apilla. From this region a new 

 hair-shaft may develop when the hair is shed, periodically or non- 

 periodically as the case may be, often by the formation of a new 

 papilla. The colour of the hair is due to three causes : — Firstly, 



