The Senses. 247 



Use of Pain. Pain is a warning of over-use or injury 

 The milder nerve impulses that cause slight discomfort 

 ought to be sufficient to call attention to the condition. But 

 often these first reports are neglected. Fqr instance, over- 

 use or abuse of the eyes may cause irritation, that is allowed 

 to go unheeded. The person may show the effect, by rub- 

 bing the eye, but, being absorbed in study, may fail to 

 stop reading and go on until there is actual pain. When 

 the first warnings are not heeded, pain follows and demands 

 attention. 



Pain in the Skin. While the internal organs are ordina- 

 rily without feeling, the skin is especially sensitive. v The 

 skin senses stand guard at the outposts of the body's 

 camp, and give warning of approaching danger. /!No 

 enemy may enter without being discovered by these keen 

 sentinels, and the alarm is given. In amputating a limb 

 the chief pain is in cutting through the skin. It is a com- 

 fort to know that the more severe wounds do not cause 

 pain in proportion to their extent. 



Hunger and Thirst. The cause of these sensations in 

 a healthy body is plainly the need of food and water 

 throughout the system. The sensation of thirst seems to 

 be in the throat, and the longing may be somewhat re- 

 lieved by merely moistening the throat. So hunger may, 

 for the time, be appeased by filling the stomach with indi- 

 gestible material. But the sensation soon returns. The 

 system has a crying need, and it is not to be put off. 

 That these sensations are really demands made by the 

 body as a whole may be shown by the fact that they are 

 permanently relieved by introducing food and water into 

 the body (by the rectum, for instance), in which case the 

 throat and stomach have nothing given them directly. 



