378 THE SENSORIAL FUNCTIONS. 



are here found to be divided to an extreme 

 degree of minuteness. 



When examined with the microscope, this ex- 

 ternal surface presents a great number of minute 

 projecting filaments. Malpighi first discovered 

 this structure in the foot of a pig ; and he gave 

 these prominences the name of papillce. It is 

 probable that each papilla contains a separate 

 branch of the nerves of touch, the ultimate 

 ramifications of which are spread over the sur- 

 face ; so that we may consider these papillae, 

 of which the assemblage has been termed the 

 corpus papular e, as the principal and immediate 

 organ of touch. This structure is particularly- 

 conspicuous on those parts of the skin which are 

 more especially appropriated to this sense, such 

 as the tips of the fingers, the tongue, and the lips : 

 in other parts of the surface, which are endowed 

 with less sensibility, the papillae are scarcely 

 visible, even with the aid of the microscope. 



The surface of the corium is exquisitely sen- 

 sible to all irritations, whether proceeding from 

 the contact of foreign bodies, or from the im- 

 pression of atmospheric air. This extreme sen- 

 sibility of the corium would be a source of con- 

 stant torment, were it not defended by the cuticle, 

 which is unprovided with either blood-vessels or 

 nerves, and is, therefore, wholly insensible. For 

 the same reason, also, it is little liable to change, 

 and is thus, in both respects, admirably calcu- 



