THE HAIE. 259 



spends to a papilla of the skin. It is ovate or fungiform, ^ to 7 J^ 

 of an inch long, T ^<y to 5 J of an inch broad, and is connected with 

 the fibrous tissue of the sac by a pedicle. Its surface is perfectly 

 smooth, and it consists, like the cutaneous papillae, of an indistinctly 

 fibrous tissue, with scattered nuclei and granules, but no cells. Nei- 

 ther Hassall, Giinther, nor Kolliker has found in it either vessels 

 or nerves. In some animals, however, the vessels may easily be 

 seen; and we must not yet positively infer that they do not exist 

 in the papillae of human hairs also. 



Ghemica I Composition of Hair. 



This subject is still not sufficiently understood; but the hairs are 

 chiefly composed of a nitrogenized substance (keratine), soluble in 

 alkalies, and insoluble in boiling acetic acid. Mulder considers that 

 10 per cent, of sulphamide is combined with this nitrogenized com- 

 pound. Scherer finds 10 per cent, of the hairs to be sulphur. Hairs 

 also contain a considerable amount of dark or clear fatty matter. 

 Chemical analysis does not discover any special pigment, though 

 the microscope does, as has been seen (p. 255). 



The ash of hair amounts to 1 to 2 per cent., in which are found 

 oxide of iron (more in dark hair), oxide of manganese, and traces 

 of silica. Jahn found phosphate of magnesia and sulphate of alu- 

 mina in white hairs ; and copper occurs in the greenish hairs of 

 those who work in copper and brass. (Langin.) 



Hairs withstand putrefaction better than any other part of the 

 organism. Even those of mummies are found to be quite un- 

 changed. Hence, also, the hair is preserved as a cherished relic of 

 the departed. Metallic oxides color it as they do the epidermis. 

 Hence the salts of silver and manganese blacken the hair, a sul- 

 phuret of these metals being produced. Chlorine bleaches it after 

 prolonged action. 



Wool and bristles do not differ essentially in composition from 

 hair. Scherer finds, however, that feathers differ much from the 

 other horny tissues, and especially from hair. Gorup-Besanez found 

 a considerable quantity of silica in feathers. 



Physical Properties of Hair. 



The hairs are quite elastic. They stretch, without breaking, to 

 nearly one-third more than their original length ; and if stretched 

 only one-fifth, they contract again so perfectly that they permanently 

 remain only -fa longer than at first. ( Weber.) Still, their strength 



