KIDNEYS, SKIN, AND GENERAI, EXCRETION. 



403 



tutes the entire remainder of the shaft. It consists of deli- 

 cate fibers closely packed together, running of course in the 

 longitudinal direction of the shaft. Finer investigation re- 

 veals that these fibers are in turn com- 

 posed of flattened and elongated cells. 

 On these dried and elongated cells rem- 

 nants of nuclei may sometimes be still 

 visible. In the cells that make this 

 fibrous portion there is a deposit of pig- 

 ment to which the hair in question owes 

 its color. In older hairs air spaces may 

 arise by a kind of drying process, which 

 by their reflection of the light give to 

 the hair a grayish appearance. Such 

 hairs, when soaked in certain liquids 

 become entirely transparent, these air 

 spaces being filled up with the liquid in 

 question, but when the hair is again 

 dried the liquid evaporates, the air again 

 enters these spaces and the old color re- 

 appears. It is said by some observers 

 that the pigment of the hair, be it 

 black, brownish or reddish, is carried to 

 the cells at the root of the hair by pe- 

 culiar wandering pigment cells reach- Fig 

 ing it. 



In some cases the interior of the hair a> mouth of follicle . 6f 

 is occupied with a kind of medulla or neck; c ' root; ^^ coats of 



/. . . the dermis; /, g, outer and 



pith. ThlS pith IS COmpOSed Of rOWS Of inner root sheathes of epi- 



cells of a generally angular form. It is hal^i.^kh-ThaT^; 

 especially apt to appear in advancing m > fat ; n, an-ector muscle; 



. f , . .,.. o, papilla of cuds; s, Mal- 



years, and the whiteness of hair is usu- P i g hian layer; , sebaceous 

 ally due to the contained air which lies glands - 

 in the spaces among these cells, and in some instances ac- 

 tually in the cells. These air spaces are of course pro- 

 duced by the drying of the hair in its exposure to the 

 atmosphere. 



,IN 

 LONGITUDINAL SECTION. 



(After Biesiadecki.) 



