DIGESTION AND FOOD. 45 



meals are digested and carried into the intestinal canal, and 

 the stomach is left without food, in about three hours and a 

 half, (56, p. 33;) and if they were composed of the most 

 digestible articles, this time would be much less. Yet hun- 

 ger does not usually return in less than five or six hours. 

 This leaves the stomach empty nearly half the time, without 

 any craving desire of food. 



85. So certainly is the desire of food the result of wants 

 of the system, in connection with the power of, and readi- 

 ness for digestion, that in some diseased states of the system, 

 where both these conditions exist, but no communication 

 between the stomach and the blood-vessels, the appetite is 

 ravenous. 



86. The wants of the whole body for more nutriment are 

 communicated first to the stomach, and thejice to the brain. 

 Here is the real sensation of appetite. It therefore is neces- 

 sary, not pnly that the stomach should be in sound condition, 

 but also that the brain be in a condition to recognize this 

 feeling of want. This feeling is conveyed through the nerves 

 from the stomach to the brain, and there perceived and rec- 

 ognized. If, then, the nerve of the stomach be diseased or 

 divided, there can be no communication from this organ to 

 the brain, and hence no sensation conveyed, and no. hunger 

 felt. Some physiologists have tried the experiment of cutting 

 the nerves which connect the stomach with the brain in dogs. 

 The consequence was, that the animals seemed to have lost 

 all sensation of appetite, and although they had been long 

 deprived of food, and were really in need of it, they did not 

 appear to feel or to understand the want of it. 



87. The appetite, then, is felt in the brain ; but it is not 

 perceived, nor are we conscious of it, unless we can give 

 attention to it. It not unfrequently happens that one is so 

 intently engaged in any pursuit, that he forgets his hours of 

 eating and his own necessities. Students are sometimes so 

 devoted to their books, that their meals do not occur to them. 

 Men who are absorbed in any care or anxiety pay less than 

 due attention to, and do not perceive, their craving sensations. 



