48 PHYSIOLOGY AND HEALTH. 



with many outward and inward circumstances. They differ 

 with the manner of life, and with the quantity and energy of 

 exercise. The laborious and active have more hunger than 

 the idle and the slow. Children and youth who are growing 

 in stature, convalescents who are regaining lost flesh, have 

 more imperative appetites than others. Appetite is more 

 keen when the body is in full vigor, and all the functions 

 are performed with the most energy. When the blood flows 

 freely and the muscles play smoothly, when the mind is 

 buoyant and the spirit joyous, the appetite boldly indicates 

 a want of food in the whole system, and a ready power of 

 the stomach to digest it, and convert it into the nutriment 

 of the blood. 



92. Appetite is usually the sign of digestive power. Cer- 

 tainly there is no vigorous digestion without it. When the 

 digestive organs, nerves, and brain, are apparently in good 

 condition, and we are attentive to the warnings of the stom- 

 ach, if then we feel no hunger, we may be assured that the 

 stomach craves no food because it cannot digest it. How- 

 ever long it may have been without food, if it do not by its 

 hunger declare its readiness and ability to convert it into 

 nutriment for the blood, it is useless to eat. It is even worse 

 than useless; for whatever is then eaten cannot be changed 

 to pulpy chyme, nor to milky chyle, nor can the lacteals ex- 

 tract from it nourishment to feed the exhausted blood, or the 

 wasted body. Food, then, eaten when we are not hungry, 

 gives weakness and oppression, and not strength and vigor. 

 It causes pain rather than the feeling of comfort, that follows 

 or accompanies good digestion. 



93. On the other hand, appetite is not always evidence of 

 digestive power. In some states of dyspepsia there is a vo- 

 racious desire of food, without corresponding power in the 

 stomach to digest it. There is sometimes a diseased and 

 continual irritation in this organ, which suggests to the brain 

 the want of food as the only means of allaying it. If food, 

 in these cases, be eaten according to the appetite, or if, in 

 some cases, any food be taken, however urgent the hunger, 



