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 granules 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. 



Fig. 150. From a Section QQ7 TVV.-T * .,.....r *;... 



through Human Scalp, showing ^7. Wew formation 



a degenerating Hair. of hair (Fig. 150).- 



a. The epidermis \ b, the hair: c, the T? VP1 . V Tiaiv VA if fiiiA and 



outer root-Bbeath of the bir loiii- -i^veiy nan, DC it nne ana 



cle;d, the sebaceous follicle \e, the (j>, nr f m . fV,i P k onrl Irmo- 



arrector pili ; /, a cyst in-own out kUOrt Ol UllCK aild lOllg, 



if the outer root-sheath; g, the nnrlov nrkvmal r>rvnrlifirm 



rudr-knoh ; ft, the new outgrowth UIKiei normal COliaitlOllS, 



of the diitcr root -sheath; i, the ]^o<^ rvnlv a limifprl 



-tw papilla. (Atlas.) nab oni y & lllllltea 



