68 TOUCH AND SENSATION. 



The nervous tissue of the skin is thus not only an 

 important instrument for receiving and conveying 

 to the mind accurate impressions in regard to tin 

 properties of external objects, but it is even essen- 

 tial to our continued existence. The pain which is 

 caused by injuries is no doubt very disagreeable, but 

 in its uses it is a positive blessing, in warning us 

 against the danger, and even certain destruction 

 which would speedily overtake us if we had no such 

 monitor at hand. If we had no nerves on the sur 

 face to communicate to us a lively impression of 

 cold, we might inadvertently remain inactive in a 

 temperature which would not only suspend perspira- 

 tion, but benumb the powers of life ; or we might, 

 on the other hand, approach so near the fire or boil- 

 ing fluids as to have the organization destroyed be- 

 fore we knew : whereas, by the kind interposition 

 of the nerves, we cannot, when perspiring freely, be 

 exposed to the cold air without an unpleasant sen- 

 sation being experienced, impelling us to attend to 

 our safety, and to keep up our heat either by addi- 

 tional clothing or by active exercise. When the 

 nervous and vascular parts of the skin are both in 

 healthy action, a pleasant soft warmth is felt over 

 the body, which is in itself a delight, and which gives 

 to the mind a lightness and hilarity, or pleasant con^ 

 pciousness of active existence, the very opposite of 

 the low arid languid depression which so generally 

 accompanies continued defective action in the skin, 

 and which forms a marked feature in many nervous 

 Affections. 



For the due exercise of Sensation, the nerves 

 must be in a proper state of health. If, for example, 

 the cuticle protecting the nervous papillae be abraded, 

 or removed by vesication, the naked nerves are too 

 powerfully stimulated by the contact of external 

 bodies, and instead of receiving and transmitting the 

 usual impressions of heat, cold, figure, and hardness 

 they conjmunicate scarcely any feeling except that 



