SKIN SENSATIONS. 535 



and past perceptions, as to the intensity, position, quality, etc., of 

 the external influence. 



SKIN SENSATIONS. 



The sensations arising from the many impulses sent from the 

 skin come under the head of special sense, and are commonly 

 grouped together under the name of the Sense of Touch. This 

 special sense may, however, be resolved into a number of specific 

 sensations, each of which might be considered as a distinct kind 

 of feeling, but usually are regarded as simply giving different 

 qualities to the sensation excited by the skin. These sensations 

 are : (1.) Tactile Sensation, or sensation proper, by means of which 



FIG. 208. 



Drawing from a section of injected skin, showing three papillae, the cen- 

 tral one containing a tactile corpuscle (a), which is connected with a med- 

 ullated nerve, and those at each side are occupied by vessels. (Cadiat.) 



we appreciate a very gentle contact, and recognize the locality of 

 stimulation, and judge of the position and form of bodies; (2.) 

 the sense of pressure; (3.) and the sense of temperature. 



The variety of perceptions derived from the cutaneous surface, 

 and the large extent of surface capable of receiving impressions, 

 make the skin the most indispensable of the special sense organs, 

 though we value this source of our knowledge but little. If we 

 could not place our hands as feelers on near objects to investigate 

 their surfaces, etc., we should lose an important source of infor- 

 mation that has contributed largely to our visual judgment. 



