96 HUMAN BIOLOGY 



Studies based on Table. - -What nuts are rich in proteids ? What 

 fruits? What animal foods? What legumes? What grains? What foods 

 are rich in fats? What are rich in carbohydrates? Which grains have 

 much starch? Which nut? Which fruits have much sugar? A family 

 was living chiefly on corn bread, potatoes, syrup, cakes, and sweetmeats : 

 what two of the four food stuffs were deficient in their diet? Another 

 family lived chiefly on fat pork, bread, rice, vegetables, and fruit : which 

 food stuff was deficient ? A dozen eggs weigh \\ Ib. Which give 

 cheaper nourishment, eggs at 15 cents a dozen or beef at 15 cents a 

 pound? Which is cheapest among the foods abounding in proteid? 

 Fat ? Carbohydrates? Which is cheaper food, a pound of beef at 20 

 cents or a pound of pecans at the same price? (Fig. 101.) What food 

 contains most water? Least water? Which of the foods abounding in 



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proteid is costliest? Cheapest? Notice that nearly all foods contain- 

 ing much proteid are costly. Water and woody fiber are not counted 

 as nutriment. What weight of nutriment in I oz. of cow's milk ? If a 

 quart of whole milk costs 12 cts., what is a quart of skimmed milk 

 worth ? 



How the Right Proportions of Fuel Foods and Proteid are reached by 

 Different Nations. -- Milk has an excess of nitrogen, and oatmeal an 

 excess of carbon ; oatmeal and milk form a popular food with the 

 Scotch. Potatoes are mostly starch and water, and an Irishman who 

 tried to live on potatoes alone would have to eat seven pounds a day 

 to get enough proteid. The Irish peasant keeps a cow and chickens ; 

 by eating milk and eggs he gets along on half the amount of potatoes 

 named above. The Mexicans eat bread made of corn meal, and supply 

 the proteid by using beans as a constant article of diet. Hundreds of 

 millions of people in Asia (the Hindus, Chinese, and others) subsist 

 mainly on rice, which contains only five per cent of proteid and no fat ; 

 the chief addition they make is butter, or other fat, and beans, which 

 contain vegetable proteid. 



Outline of Digestion. The food is made soluble in the 

 alimentary canal and is absorbed by the blood vessels and 

 lymphatics in its walls. This canal is about thirty feet 

 long (Figs. 89, 90) and consists of - 



(1) The mouth, where the food remains about a minute, 

 while it is chewed and mixed with the saliva ; the saliva 

 changes a portion of the starch to malt sugar. 



(2) The gullet, a tube nine inches long, running from 



