ss 1'iiiLosoi'iiY o*: ZOOLOGY. 



passes through the corium, mucous web and cuticle. It 

 usually raises up small scales of this last layer, which soon 

 become dry and fall off, but do not form the external co- 

 vering of the hair, as some have supposed- 



The hair itself consists of an external horny covering, 

 and a central vascular part, termed medulla or pith. This 

 horny covering consists o numerous filaments placed la- 

 terally, to which different kinds of hair owe their striated 

 appearance. These filaments appear to be of unequal 

 lengths ; those nearest the centre being longest ; and, con- 

 sequently, the hair assumes the form of an elongated cone, 

 with its base seated in the skin. This form gives to the 

 hair that peculiar property, on which the operation of felt- 

 ing depends. 



When we take hold of a hair by the base with the fingers 

 of one hand, and draw it between two of the fingers of the 

 other, from the root towards the point, it feels smooth to 

 the touch ; but if we reverse its position, and draw it be- 

 tween the fingers from the point to the root, we feel its 

 surface rough, and it offers a considerable resistance. 

 The surface of the hair must, therefore, consist of emi- 

 nences pointing to the distal extremity. In consequence of 

 this structure of the surface, if a hair is seized at the middle 

 between two fingers, and rubbed by them, the root will'gra- 

 dually recede, while the point of the hair will approach 

 the fingers ; in other words, the hair will exhibit a progres- 

 sive motion in the direction of the root, the imbricated sur- 

 face preventing all motion in the opposite direction. 



It is owing to this state of the surface of hairs, that 

 woollen cloth, however soft and pliable, excites a disagree- 

 able sensation of the skin, in those not accustomed to wear 

 it. It likewise irritates sores, by these asperities, and excites 

 inflammation. The surface of linen cloth, on the other hand, 

 j'eels smooth, because the fibres of which it consists, possess 



