802 



MAMMALIA. 



Fig. 404. 



sists of the cutis or vascular true skin, of the epidermis or cuticle, 

 and of a thin layer of pigment interposed between the two, which is a 

 diversely- coloured secretion deposited, like the cuticle, upon the surface 

 of the cutis. 



(2347.) The hairs that cover the quadruped, whatever be their form 

 or thickness, are cylinders of horny or cuticular substance, that grow 

 upon so many minute vascular pulps, from the surface of which the 

 corneous material is perpetually secreted. Some kinds of hair are per- 

 manent, and, if constantly cut, 

 will continue to grow during 

 the whole life of the animal ; 

 such is the hair of Man, and 

 that which forms the mane and 

 tail of the Horse: but gene- 

 rally the hair is shed at stated 

 periods, to be replaced by a 

 fresh growth. For the most 

 part these structures are so 

 minute, that the apparatus 

 employed in forming them 

 escapes observation; but in 

 very large hairs, such as those 

 that compose the whiskers of 

 the Seal, or of the Lion, it is not 

 difficult to display the organs 

 by which they are secreted. 

 The appended figure, taken 

 from one of the drawings in 

 the Hunterian collection, re- 

 presents a section of the lip of 

 a young Lion; and in it all 

 the parts connected with the 

 growth of the larger hairs are 

 beautifully displayed. A bulb 

 or sacculus, formed by an inward reflexion of the cutis (fig. 404, B, e\ 

 and lined by a similar inflexion of the cuticle (/), contains in its fundus 

 a vascular pulp- (###), well supplied with large vessels and nerves (h). 

 It is from the surface of the pulps (g) 9 exhibited upon a magnified scale 

 at A, that the horny stem of the hair is gradually secreted; and its 

 length of course increases in proportion to the accumulation of corneous 

 matter continually added to the root. 



(2348.) Various are the appearances of epidermic appendages in every 

 way analogous to hair both as relates to their composition and mode of 

 growth, and widely different the uses to which they may be converted : 

 the wool of the Sheep, the fur of the Rabbit, the spines of the Hedge- 



Section of the lip of a young Lion. 

 (After Hunter.) 



