284 



ELEMENTS OF HISTOLOGY, [chap, xxxiv. 



stance, cuticle, and inner root-sheath and the con- 

 tinual new production of cells over the papilla causes a 

 gradual progression and con- 

 version of the cells, and a 

 corresponding growth in 

 length of the hair shaft. 



Pigmented hairs, as men- 

 tioned above, contain pig- 

 ment gran ules between i. e. , 

 in the interstitial substance 

 cementing together the 

 hair fibres, and diffuse pig- 

 ment in their substance. 

 According to the amount 

 of these pigments, but es- 

 pecially of the interstitial 

 pigment granules (Pincus), 

 the colour of the hair is of 

 a greater or lesser dark 

 tint. In red hairs there is 

 chiefly diffuse pigment. In 

 white or fair hairs neither 

 the one nor the other 

 pigment is present ; in grey 

 there is air at least in 

 the superficial layers of the 

 hair substance, besides ab- 

 sence of pigment. 



Sleek hairs are circu- 

 lar, curly oval, in cross-sec- 

 tion. 



387. New formation 

 of hair (Fig. 150). - 



TPtTciv-iT Vioiy Vo if -fino anrl 



-^veiy hair, be it Due and 



cnrkT .f rr> fninV anrl Inner 

 Snort Or ttllCK ana long, 



i 1Tlr |/}v nnrrnnl nrmrlifirvn 

 Under normal Conditions, 



a liTrntprl 

 limited 



Fig. 150. From a Section 



through Human Scalp, showing 



a degenerating Hair. 



o. The epidermis ; 6, the hair ; c, the 

 outer root-sheath of the hair folli- 

 cle ; d, the sebaceous follicle ; e, the 

 arrector pili ; /, a cyst grown out 

 of the outer root-sheath ; g, the 

 hair-knoh ; h, the new outgrowth 

 of the outer root -sheath; *, the 

 new papilla. (Atlas.) 



