HAIR. 271 



cupied by a papilla furnished with blood vessels and nerves, 

 on which the bulb of the hair immediately rests ; and that 

 it is owing to this papilla that the base of the bulb, when 

 removed, exhibits a concavity. This description, in the case 

 of tactile hairs, may be correct, but is surely not so when 

 applied to hairs in general. Each hair does indeed rest upon 

 a papilla, but it is one which is destitute of blood vessels 

 and nerves, and which is cut off from all direct vascular 

 communication by the cul-de-sac formed by the outer lamina 

 of the sheath. This papilla may be described as a compound 

 cellular vesicle, and is probably the true germ of the hair ; it is 

 on it that the bulb of the hair is situated, and which occasions 

 the depression which this generally displays when it has been 

 forcibly extracted. This gerrn is best seen in grey and light 

 coloured hairs. 



GROWTH OF HAIR. 



The growth of hair takes place at the root, and is the 

 effect of the development of new cells which is continually 

 in progress in the bulb, and which afterwards become 

 modified into those of the scaly cortex and fibrous stem ; 

 these new cells, coming behind the older ones, continually 

 press them forwards, and thus occasion the elongation of 

 the hair. 



But the elongation of each hair takes place in a manner 

 very different from that just mentioned, not from the de- 

 velopment of new cells, but by the gradual elongation and 

 extension of the cells already formed after they have quitted 

 the bulb, and when they come to form the shaft of the hair. 

 This mode of elongation, it can scarcely be called develop- 

 ment, is proved by the gradual tapering of the hair which 

 takes place after the point has been removed: of the truth of 

 this fact not the slightest doubt can be entertained. 



At the period of puberty a growth of hair takes place 

 in certain situations in which previously it was not ap* 

 parent, as on the chin, cheeks, in the axilla?, and on the 



