296 UUNGER AND THIRST. 



Foster puts it, "The constantly smoldering embers of com- 

 mon sensibility may be at any moment fanned into the flame 

 of pain." 



In the real "special senses,"- sight, hearing, smell, taste, 

 touch, and temperature sense, we refer the sensation to some 

 external' object, whereas general sensations are subjective, 

 referred to our bodies. Ordinarily we do not localize the 

 common sensations, and a farther indication of the relation- 

 ship of pain and general sensation is in the lack of complete 

 localization of pain. Slight pain, especially in the skin, may 

 be closely located, but severe pain tends to become indefinite 

 and diffuse. So we may class both the muscular sense and pain 

 with the " general " rather than with the " special " senses. 



Hunger and Thirst. The cause of these sensations in a 

 healthy body is plainly the need of food and water throughout 

 the system generally. The sensation of thirst manifests itself 

 in the throat, and the longing may be temporarily relieved by 

 merely moistening the throat. So hunger may, for the time, 

 be appeased by filling the stomach with indigestible material. 

 But the sensation soon returns. The system has a crying 

 need, and it is not to be put off by any such frauds. 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. Since, however, food and 

 drink naturally enter by the throat and stomach, the mucous 

 membrane of these organs has become spokesman of the body 

 for its demands. 



The Sense of Taste. We have seen that the tongue is 

 a very muscular organ, and that when we are eating it helps 

 to keep the food between the teeth, and that it does the chief 

 part of the work in beginning the process of swallowing. 



