306 



HITCHCOCK'S ANATOMY 



be a source of misery. But these delicate nerves are pro- 

 tected by an insensible membrane, which, though hard, elas- 

 tic, and a very perfect guard of these faithful sentinels, per- 

 mits all the necessary impressions to pass through them. The 

 epidermis also guards the most delicate parts in a careful man- 

 ner, by thickening its substance over the ends of the fingers, 

 and in all places where sensation is most acute. It is also 

 speedily renewed where friction or accident removes it, as on 

 the palms of the hands and soles of the feet. 



536. To prevent Absorption. — Another important use of 

 the epidermis is to prevent undue absorption. For the lym- 

 phatics only penetrate the corium, and cease at the under sur- 

 face of the epidermis. Consequently but very little fluid can 

 enter these vessels unless the epidermis is removed or satu- 

 rated with fluid. Were it not for this protection, almost every 

 liquid substance brought in contact with the surface of the 

 body would at once be introduced into the general circulation, 

 thus exposing the system to serious danger by absorbing poi- 

 sonous matter. 



537. To Prevent Excessive Perspiration. — Danger from 

 an opposite direction is also warded off by the impenetrability 

 of the epidermis. Were it not for the tortuous direction which 

 the outlets of the sweat glands take as they empty themselves 

 upon the surface of the body, an excessive amount of water 

 w T ould be set free, and thus greatly reduce the system. But 

 owing to this arrangement of sweat ducts, it is only when the 

 system is very much stimulated that any considerable amount 

 of w^ater can be discharged by sweating. Were not this the 

 case, the body would often be reduced to a low state from the 

 loss of the watery portion of the blood, as is sometimes seen 

 in excessive sweating. 



538. Use of the Corium — Contains the Blood-Vessels 



536. What is the use of the epidermis to prevent undue absorption ? 537. How does 

 the epidermis prevent undue perspiration? What harm would result from excessive 

 sweating ? 



