210 PHYSIOLOGY AND HEALTH. 



CHAPTER VII. 



Skin Seat of Touch. Sensibility of Skin differs in different Parts, 

 and in different Persons. If the outer Skin is- thick or foul, the 

 Sensations of the inner Skin are dull. Sense of Touch can be 

 cultivated Blind have acute Sense of Touch. 



501. The sense of touch is situated in the skin. It is 

 not in the cuticle, which is insensible, but it is in the true 

 or inner skin, which is very sensitive and exceedingly alive 

 to pain, and suffers from contact with any matter, however 

 soft and bland. Strip off the outer skin and expose the layer 

 beneath, and this, which before was comfortable when pro- 

 tected, will now, in its nakedness, ache with pain. Even the 

 air is disagreeable to it. But this sensibility to pain is un- 

 equally distributed. The sensibility to contact, or the acute- 

 ness of the sense of touch, also differs in the various parts of 

 the skin. Some parts are more plentifully supplied with 

 nerves than others. The ends of the fingers, the lips, and 

 the face of man, and the end of the elephant's trunk, have 

 more nerves and more sensibility than the back or the chest; 

 these and all other uncovered parts have more than the head, 

 which is covered over with hair. 



502. The cutaneous sensibility is as unequally distrib- 

 uted as are the nerves. It is the greatest at the tip of the 

 fingers, and the least in the scalp. The sensibility of touch 

 is more acute in the right than the left, but the sensibility 

 in regard to heat is greater in the left than in the right hand ; 

 for. " if the two hands were immersed in warm water of the 

 same temperature, that in which the left was plunged would 

 feel the warmest." The sensibility differs very much in dif- 

 ferent individuals, so much " that that which amounts to 

 absolute torture in one is a matter of almost indifference to 

 the other." The sensibilities are more acute in the young 

 than in the adult, and in the latter than in persons of ad- 

 vanced life. They are greater in the female than in the 

 male; in the sanguine and nervous than in the phlegmatic 



