444 CHEMICAL COMPOSITION OF THE HAIRS. 



chiefly of animal matter, of some concrete white, and some 

 black oily matter; iron, oxide of manganese, phosphate and 

 carbonate of lime, silex and sulphur. The change of color to 

 gray, is said to be owing to a preponderance in the formation 

 of the white oily substance, and the development of some 

 phosphate of magnesia.* The shape of the hairs vary in differ- 

 ent parts. 



From the large size of the nerves which enter the papilla?, 

 to which the hairs are attached, they become in many animals 

 delicate instruments of touch. The formation of the hair 

 depends upon the follicle ; while this remains healthy, though 

 the hair should be removed by its roots, it will again be repro- 

 duced. 



Boucheron in a recent work on the hair, says that in baldness 

 the bulbs are often only partially atrophied, a circumstance 

 which does not render hopeless the idea of their recovering 

 their original functions, and re-secreting the horny matter 

 which forms the hair, under the influence of certain stimuli. 

 Round the bulbs of the larger hairs, are found some smaller 

 ones, which, as seen in extraction of the former in some cases 

 of tinea capitis, are sometimes developed to an unusual extent. 

 It has also been frequently observed, that in many women 

 the almost imperceptible down of the face presents, after the 

 fortieth or fiftieth year of age, a great increase of development. 

 The bulbs of the hairs are obliquely and confusedly 

 implanted in the dermis hence when one straggling white 

 hair is extracted from the head, the neighboring ones speedily 

 whiten in their turn from the disturbance and injury which their 

 bulbs have suffered. 



There are many hairs, which are developed so feebly that 

 they do not pass the epidermis, but roll and curve themselves 

 under it. From accidental circumstances the energy of the 

 bulbs of these hairs is sometimes so increased, that skin which 

 had been previously smooth, becomes hairy. Boucheron, attri- 

 butes the color of the hair to a peculiar animal oil, secreted 



* C. P. Ollivier. 



