CHAP. II.] 



THE CATS GENERAL FOBM. 



23 



formed, like each claw, of modified epidermal cells, but then each hair 

 grows from a single dermal papilla only, of which it is the greatly- 

 prolonged epidermal covering. Moreover, this dermal papilla does 

 not stand up from the surface of the dermis, but is placed at the 



Fig. 7. 



A. Pacinian Body from Cat's Mesentery. 



a. Arterj'. 

 n. Nerve. 

 /. Pibroiis tissue. 



B. Touch-corpuscle. 



ca. Epithelium. 



c. Nuclei. 



71. Core, into which the nerve enters. 



bottom of a small sac, the follicle, which is a depression in the 

 cutis. The central part of the hair, or pith, is less dense than its 

 rind, or cortical substance, which is formed of very long, horny cells 

 which have coalesced. Outermost of all is the cuticle or epithelial 

 layer, formed of very thin overlapping scales. The colouring 

 matter is deposited within the outermost layer, and may be uniform 

 throughout, or may be different in different parts of the same hair. 

 Some hairs are especially slender, and have the edges of the scales 

 of their cuticle so projecting, as to form a serrated envelope. Such 

 hairs are " wool," and easily become entangled and adherent to- 

 gether by their serrations, or '* felted." True hair, such as the cat's, 

 has not the property of " felting," because its surface is smooth. 



Although hairs (like claws, and the epidermis generally) have 

 no blood-vessels, yet the sudden changes which may sometimes take 

 place in their colour, prove that nutritive modifications extend into 

 them. 



Very small vessels pass into the papillse of the hairs, which are 

 also furnished with a minute nerve, to the presence of which 

 the pain felt when the hair is pulled out is due. 



