FOOD. 123 



COMPOSITION OF THE POTATO. 

 Starch ......... 20.0 



Albuminous matter ....... 2.5 



Sugar and gum . . . .1.1 

 Fatty matter ..... . - .0.1 



Cellulose ......... 1-0 



Mineral and vegetable salts ..... 1-3 



Water ......... 



100.0 



The leguminous seeds, on the other hand, contain an abundance of 

 albuminous matter, similar in character to the caseine of milk, and 

 called u legumine." 



COMPOSITION OF WHITE BEANS. 

 Starch ......... 55.7 



Albuminous matter ....... 25.5 



Fatty matter . . . . . . .2.8 



Cellulose ...... ... 2.9 



Mineral salts ...... . .3.2 



Water ......... 9-9 



100.0 



The composition of dried peas is very similar to the above, the 

 starchy matters only being present in rather larger, the albuminous 

 ingredients in rather smaller proportion. Notwithstanding the abund- 

 ance of nitrogenous matter in leguminous seeds, its quality is inferior 

 to that contained in the cereal grains. Peas and beans also have a 

 texture which renders them comparatively difficult of digestion, and 

 requires long boiling to fit them for use as food. The same is true of 

 many juicy and saccharine roots, such as beets and parsnips, which 

 appear to have a comparatively soft consistency, but which nevertheless 

 need prolonged boiling. The object and effect of the cooking process 

 in vegetables generally is to disintegrate and soften their texture, and 

 particularly, by the aid of heat and moisture, to bring their starchy 

 ingredients into the hydrated condition. Raw starch is nearly or quite 

 indigestible by man, and if taken into the stomach under that form will 

 often pass unchanged from the bowels ; but when thoroughly hydrated 

 it is easily acted on and transformed into glucose by the digestive fluids. 

 It is for this reason that starchy vegetables require more thorough cook- 

 ing to render them digestible than most kinds of animal food. 



Beside the more solid kinds of vegetable food, many of the pulpy and 

 succulent fruits and herbaceous substances are valuable as an addition 

 to the nutritive regimen celery, lettuce, parsley, spinach, with all the 

 sweet fruits and melons, are used with advantage either in the raw or 

 cooked form. They introduce into the system a large number of salts 

 of the vegetable acids, such as malates, tartrates, and citrates, the 

 privation of which for a long time is one of the inducing causes of 



