OF THE HAIRS. 



that nothing can be made out of it. It is only in the hair-sacs of 

 white hairs that its outlines can be more frequently distinguished 

 without wholly isolating it, especially by the help of a little 

 pressure. Reagents, on the other hand, avail nothing, for they 

 attack the papilla to about the same extent as the bulb, with 

 the sole exception of a weak solution of caustic soda, in which 

 it retains its outlines, for a time at any rate, whilst the cells of 

 the bulb are freed and may be pressed out of the sac. The 

 papilla is ovate or fungiform, \ — ^j" long, T ' T — ^'" broad, and 

 is connected with the layer of connective tissue of the sac, by a 

 pedicle : it has sharp contours and a perfectly smooth surface, 

 and in its structure completely agrees with the papillse of the 

 cutis, consisting of an indistinctly fibrous connective tissue 

 with scattered nuclei and fat-granules, but not of cells. I 

 have taken every pains to discover vessels and nerves in the 

 isolated papilla, but in vain; even acetic acid and dilute 

 solution of caustic soda, which in general do such excellent 

 service in these cases, have failed, and Hassall and Giinther met 

 with the same results. It must not hence be concluded, that 

 the papilla contains no vessels or nerves, for we know that in 

 other places, where vessels do certainly exist, they often com- 

 pletely escape the eye; as, for example, in the dermal papilla 

 and in the villi ; and with respect to the nerves, in the papillse 

 of the cutis. In some animals the vessels may very readily be 

 seen. 



§ 61. 



The root sheath, or the epidermic investment of the hair- 

 sac, is continuous with the epidermis around the aperture of 

 the follicle, and may be divided into an external and an internal 

 layer, which are distinctly defined from one another. 



The external root-sheath is the continuation of the stratum 

 Malpighii of the epidermis, and lines the whole hair-sac, resting 

 for its lower half on the transparent membrane above de- 

 scribed ; higher up, when this and the transverse fibres are 

 absent, it lies directly upon the longitudinally fibrous layer. 

 Its structure corresponds exactly with that of the stratum 

 Malpighii, even in the having the outermost cells, which in the 

 Negro, according to Krause, are always brown, and in whites 

 are so, at least in the hairs of the labia majora, towards the 



