THE EPIDERMIS. 39 



cortex (k), and medulla (/). In the former we see the cells 

 becoming longer and flatter, until finally they are quite dry, 

 irregular, elongated cortical plates of 0.075 1 mm., and fre- 

 quently non-nucleated, in close union, forming the outer por- 

 tion of the hair shaft. A diffuse coloring matter, light in 

 blondes, deeper in dark-haired individuals, permeates the 

 whole. Pigment granules and the finest air vesicles may ap- 

 pear in the spores and clefts. 



The medullary substance does not, by any means, occur in 

 every hair, since in all lanugo hairs and also in many of those 

 of the head it may be entirely or partially wanting. At first 

 (Fig. 39, k), the cells of the 



hair bulb are perceived to be a'""M "^ e ^^ ^^"5^5 



transformed into larger polyne- 7?ff 



dral elements of 0.015 1 to 0.0226 

 mm. Further above follows m-^-h 



the drying and shrinking of the ^MJP^ ~" * 



elements, which have in the 



m 



mean time become non-nucleat- „, „ ,. ,-..,. 



Fig. 41. — Rudiments of the hair of a rul- 

 ed. Very Small air Vesicles man embryo of .6 weeks : a 6, epidermal 

 J layer; m. m, cells ot the rudiments of the 

 dlter the innumerable Small h l Llir: *> structureless membrane covering 



them . 



spaces. A white hair thus re- 

 ceives its appearance, while in colored hairs the serrated sub- 

 stance glistens through the coloring of the cortex, as if 

 tinged. 



We have still one structure remaining, the epidermis or 

 cuticle of the hair (Fig 39,/, 40, b). A double layer of hy- 

 aline obliquely standing cells covers the hair, as long as it is 

 surrounded by the sac. With the latter terminates the outer 

 cell layer, but not so the inner one. This covers the free 

 hair, as a system of quite obliquely arranged, flat, non-nu- 

 cleated lamellae, covering each other in a tile-like manner, like 

 a scaly coat of mail. Not unfrequently, after pressure and 

 maltreatment, the lamellae present the appearance of regular 

 transverse fibres (Fig 39, /*). 



Hairs are found over nearly the whole body, as so-called 

 lanugo hairs, and in limited places as thicker, coarse hairs. 



