232 GENERAL ANAT6MY. 



as follows: it is attached by its base, which is hollow, to the 

 surface of the papilla; in addition to this, the epidermis, after 

 being brought from the surface of the skin to the mouth of the 

 bulb, is reflected on the base of the hair, is united to, and con- 

 founded with its surface; the hair is thus strongly connected 

 with the skin, and can not be drawn with any force, without 

 occasioning pain; the separation of the hair in the dead body, 

 is effected by the same causes, which detach the nails and epi- 

 dermis from the skin. 



339. The stem of a hair consists of a horny sheath that is 

 diaphanous, and nearly colourless, and of an internal coloured 

 substance, generally described as consisting of a certain num- 

 ber of filaments, said to be from five to ten, moistened with a 

 colouring matter; some have asserted this sheath is filled with 

 a spongy substance similar to that found in the stems of fea- 

 thers; others have pretended that the internal filaments are 

 vascular; it has also been affirmed that a hair consists of one, 

 single, homogeneous, horny filament, which is not probable; 

 Mascagni states it to be entirely formed of absorbent vessels. 

 It appears, on the contrary, that the hairs, like the epidermis 

 and horn, are totally deprived of vessels and nerves; that they 

 simply consist in a prolongation of the two layers of the cor- 

 pus mucosum, the horny layer, and the coloured layer, to which 

 is joined the epidermis. 



340. The colour of the hairs generally, corresponds to that 

 of the skin and eyes. In those individuals who have coloured 

 spots, or albinous spots, the hairs are coloured in the former, 

 and white or colourless in the latter. They are very strong, 

 and support considerable weight without breaking. They are 

 easily torn or split lengthwise. They are very hygroscopic, 

 moisture swells and lengthens them, dryness shortens them: 

 Saussure has profited by this phenomenon in the construction 

 of the hygrometer that bears his name. They are idio-electric. 

 They depolarize light, and according to Dr. Brewster, their 

 axes are perfectly neuter, being parallel and perpendicular to 

 the axes of the hair. 



According to Mr. Hatchett, a continued ebullition of the 

 hairs, deprives them of a little gelatine, while the remaining 



