688 MAMMALIA. 



animal ; such is the hair of Man, and that which forms the mane 

 and tail of the Horse : but generally 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, represents 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 reflection of the cutis (Jig- 318, B, e), and lined 

 by a similar inflection of the cuticle (/), contains in its fundus a 

 vascular pulp (g, g, $), well supplied with large vessels and nerves 

 (h). It is from the surface of the pulps (g), exhibited upon a mag- 

 nified scale at A, that the horny stem of the hair is gradually se- 

 creted, and its length of course increases in proportion to the 

 accumulation of corneous matter continually added to the root. 



(789.) Various are the appearances, and widely different the 

 uses, to which epidermic appendages, in every way analogous to hair, 

 both as relates to their composition and mode of growth, may be 

 converted : the wool of the Sheep, the fur of the Rabbit, the spines 

 of the Hedgehog, the quills of the Porcupine, the scaly covering 

 of the Manis, and even the armour that defends the back of the 

 Armadillo, are all of them but modifications of the same struc- 

 tures, adapted to altered conditions under which the creatures live. 

 Even the horn upon the snout of the Rhinoceros is but an ag- 

 glomeration of hairy filaments, formed upon a broad and com- 

 pound pulp. The nails and claws that arm the fingers and toes, 

 the corneous sheath that invests the horns of the Ox and Ante- 

 lope, nay, the hoofs of herbivorous quadrupeds, are all epidermic 

 secretions from the vascular cutis ; or, in other words, are hairs 

 altered in their form and extent, according to the exigencies of the 

 case. 



(790.) Widely different, however, are the so-called horns of 

 the Deer tribe, which in reality consist of bone, and, being deci- 

 duous, have to be reproduced from year to year by a most pecu- 

 liar and interesting process. No sooner does the return of genial 

 weather again call forth the dormant reproductive energies of the 

 system, than the budding antlers begin to sprout from the forehead 

 of the Stag, and rapidly expand in their dimensions from day to 



