SKIN SENSATIONS. 537 



SKIN SENSATIONS. 



Tbe sensatioDS arising from the many impulses sent from the 

 skKi 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 sensations excited by the skin. These sensations 

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

 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. 



FIG. 208. 



Drawing from a section of injected skin, showing three papillae, the central one con- 

 taining a tactile corpuscle (a), which is connected with a medullated nerve, and those at 

 each side are occupied by vessels. (Cadiat.) 



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. 

 We think we know by the look of a thing what we originally 

 learned by feeling it. If our conjunctive did not feel, we should 

 miss its prompt warning, and our voluntary movements could not 

 protect our eyes from many unseen injuries that normally never 



