VEGETABLE FOOD 



are liable to ferment in the intestine. Grapes contain 

 more albumin than almost any other fruit, while their 

 sugar is the form produced by digestion. For these 

 reasons they arft^asily digested, and are a real food. 

 Bananas also contain much albumin and sugar. Green 

 fruit is digested .with difficulty and is very liable to injure 

 the stomach. Over-ripe and decayed fruits often contain 

 poisons which produce violent sickness. Only a small 

 quantity of any fruit should be eaten at once. 



194. Tart fruits. Oranges, lemons, rhubarb, and such tart or 

 sour articles of food are often said to be "cooling" to the blood. When 

 the appetite fails, and the mouth is dry with a false thirst, their sourness 

 excites the flow of the alkaline saliva, and so the mouth and tongue 

 become moist, and the false thirst is relieved. In long voyages and 

 expeditions, when fresh food cannot be obtained, they are of value in 

 warding off scurvy. When eaten at meal times, the acid of sour fruits 

 hinders the production of the gastric juice, and thus retards rather than 

 aids digestion. In the stomach the acids unite with the mineral matters 

 of the food, and then are absorbed into the blood. Their presence in 

 the blood seems to have some effect on the nutrition and action of the 

 cells, and on this account they are sometimes given as medicine. They 

 seldom take part in building up the body, but are quickly thrown off 

 by the kidneys. The popular idea of their cooling effect is derived 

 mainly from the fact that they excite the flow of saliva, and thus render 

 the mouth moist. 



195. Nuts. Nuts contain oil, but it is doubtful if much 

 of it is emulsified and absorbed. They contain an abun-, 

 dance of albumin and starch, but their digestion usually 

 requires more time and energy than the stomach of man 

 is designed to furnish. 



196. Canned food. When food is heated so as to destroy its 

 living germs, and then is at once sealed air-tight, it will neither decay 

 nor sour, and when opened a long time afterwards it will be found to be 

 as fresh and wholesome as when it was put into the can. Thus it is 

 possible to carry fresh meat and vegetables on long voyages or to remote 



