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MANUAL OF PHYSIOLOGY. 



Green Vegetables. These contain some starch, sugar, dextrin, 

 salts, and minute quantities of proteid, and are of small nutritive 

 value. 



Potatoes contain very little proteid, but a considerable quantity 

 of starch, upon which their nutritive value almost entirely depends. 



The following table gives the relative proportions of the various 

 nutritive materials contained in some of the common vegetable 

 foods : 



The most striking points are the very large proportion of pro- 

 teid in the leguminous fruits, and the comparative richness of all 

 vegetables in starchy food-stuffs. 



Water is the great medium by the solvent power of which food 

 is made capable of ingestion. Spring water always has a certain 

 quantity of lime and other salts in solution, and in proportion to 

 the amount of salts is said to be more or less hard. Water is 

 tasteless, inodorous, and colorless when pure. Soft water, such as 

 rain water, is pure, but not so agreeable to taste as spring water, 

 and is very liable to contamination in its passage over roofs pre- 

 vious to collection. Standing water should be avoided for drink- 

 ing, owing to the probability of its containing organic matter. 



Salts. Great varieties of salts are taken into the system, of 

 which chloride of sodium forms the largest proportion. These 

 have no doubt very important functions to perform, in entering 



