OSSEOUS SYSTEM OF MAMMALIA. 75 



sions of temperature, or mere contact ; but the hand, alone, is qualified for 

 ascertaining, strictly, the size, figure, consistency, and general character 

 of objects, by the test of touch. Its palmar surface is exquisitely sensitive 

 in every part, and particularly so at the tips of the fingers, where the 

 nervous papillae are not only much developed and exposed, but, according 

 to some authors, positively erectile, if excited. The pulpy parts, beneath, 

 form adipose cushions, supported by the nails, which, from their powers 

 of resistance, manifestly tend to improve the mechanism of the organ, by 

 rendering the tips of the fingers capable of being closely pressed upon 

 external objects. 



The nails are horny plates, which arise out of the true skin, and grow 

 from a pulpy root : they are closely attached to the soft parts, and cannot 

 be separated without intense pain. Besides serving as a support and de- 

 fence to the tips of the fingers, they act, also, as a barrier, between the 

 nerves of the part beneath, and external bodies, so as to intercept the com- 

 munication of definite impressions to those nerves, in order that the nervous 

 energy may be the more fully concentrated on the part appropriated to 

 touch, and that the impressions there received may be vivid and unmixed. 

 Man uses the nails neither as weapons of offence, nor as scrapers for turning 

 up the earth, nor as hooks with which to climb or cling. In most of the 

 lower animals, however, these parts are of great importance in the economy 

 of their habits and modes of life, and are accordingly modified through a 

 variety of gradations. In the Lion, or Tiger, the claws are fashioned 

 into cutting-hooks (fig. 70), sheathing the last joint of the toes, and 



capable of being protruded or retracted at pleasure. In the Armadillo 

 and Mole they assume a scraper-like form, and are hard and firm 

 (fig. 71, nail of the Mole). In the Horse they form a hoof, or sheath, to 

 the extremity of the limbs (fig. 72) : yet, in every instance, they are only 

 modifications of the same organ, the thin, rounded, delicate nail, which 

 forms so elegant and appropriate a finish to the finger of the human hand. 

 As is the hand so must be the arm : that is, the structure and capa- 

 bilities of this organ will influence the mechanism of every part connected 

 with it ; and where it enjoys the highest sensibility and freedom, and is 

 the depository of a sense ministering to the mind, there must the arm be 

 so fashioned as to enable it to fulfil every purpose for which it was 

 intended. 



