244 SKIN, HAIR, AND NAILS, BY ALFRED BIESIADECKI. 



internal sheath, and form a close plexus in its substance. No 

 nerves have hitherto been found in it. It first makes its 

 appearance at the level of the neck of the follicle, and in 

 the stronger hairs of the beard forms a layer surrounding 

 their lower part, of the thickness of 0'05 of a millimeter. It 

 surrounds also the bulb, and is continuous at its base with the 

 papilla (p) which projects into the cavity of the follicle, and 

 is usually seated, by means of a peduncle, upon the internal 

 sheath of the follicle. 



The papilla of the hair exhibits a thin neck and a thicker 

 body with a conical extremity. On the average its length is 

 twice as great as its breadth. Its thickness, and not its length, 

 stands in relation to the length of the hair (Schron). 



The papilla consists of fibrous connective tissue, the fibres 

 of which proceed from the internal sheath of the follicle, and 

 are intermingled with numerous round nuclei, together with 

 well-defined round nucleated cells. Its surface is perfectly 

 smooth, and at the neck it is surrounded by the vitreous 

 membrane of the hair follicle, though this cannot be demon- 

 strated to extend over the bulb. 



Two small arteries enter the papilla. These usually unite to 

 form a single trunk towards the summit and then again divide 

 to form two emergent vessels (veins). Numerous anastomoses 

 occur between these four vessels. 



I have been able to follow non-medullated nerve fibres as far 

 as to the neck of the papilla. 



The third and innermost layer of the hair follicle is com- 

 posed of a transparent membrane Vitreous membrane hav- 

 ing a thickness of 0*005 0*008 of a millimeter, and remaining 

 unchanged both in acids and alkalies. Notwithstanding that 

 this layer appears perfectly homogeneous on section, it exhibits, 

 when viewed on the flat surface, transverse, obliquely decussating, 

 delicate fibres, and here and there also ill-defined round nuclei. 



Diluted solution of silver brings markings into view on the 

 vitreous membrane that resemble those of the walls of the 

 lymphatics (Czerny).* 



The outer surface of this membrane, which is in contact 



* Centralblatt fur die med. Wissenschaften, 1869, No. 26. 



