DIGESTION AND FOOD. 37 



ained." * Dr. Dalton thinks " a man in full health, taking 

 free exercise in the open air, requires rather more than 

 three pints of liquid daily." f 



62. The stomach acts more easily upon a large than on a 

 very small quantity of food. As the hands find it easier to 

 grasp and hold a cane than a quill or a wire, and the arms can 

 more easily clasp an armful of wood than a single stick, 

 so the muscular coat of the stomach finds less difficulty in 

 grasping and pressing upon a full meal than a little morsel. 

 The quantity of nutriment in food is not always in propor- 

 tion to its bulk ; some kinds contain very much, and others 

 very little, in the same space or weight. A pound of beef is 

 more nutritious than a pound of bread, and a pound of bread 

 contains more nutriment than a pound of roots. 



63. Meats are very concentrated ; that js, they contain 

 great quantities of nutriment in small bulk ; and if we were 

 to live upon these alone, we should eat a small quantity 

 smaller than the stomach could manage with the greatest 

 ease to itself. This difficulty is obviated by mixing meat 

 with bread and vegetables. Some of the rude tribes in the 

 extreme northern regions live upon the coarsest and most 

 concentrated meats. But they find it better to mix this with 

 bread, potatoes, or other roots, with bran, or even sawdust, 

 for the purpose of facilitating the action of the stomach. 



64. In order that the food should be mixed the most freely 

 with the gastric juice in the stomach, it should be not only 

 well divided in the mouth, but it should be of such a nature 

 that the gastric juice can get access to all the minute par- 

 ticles, and separate them from each other. With light bread, 

 that is thoroughly baked, and somewhat dried, this is easily 

 accomplished. But heavy bread is cohesive, and the parti- 

 cles cling together and form a solid mass, so compact that it 

 would be very difficult for any fluid to penetrate it. 



65. The difference is easily shown, and is* probably famil- 

 iar to all ; if not, the experiment can be tried in one moment, 

 by throwing a piece of light, porous bread, that has been 



* On Preservation of Health, p. G2. f Physiology, p. 113. 



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