FOOD AND DRINK. 73 



food. The following experiment is recorded : " A dog 

 eating ad libitum of white bread, made of pure wheat, and 

 freely supplied with water, did not live beyond fifty days. 

 He died at the end of that time with all the signs of 

 gradual exhaustion." Death took place, not because there 

 was anything hurtful in the bread, but because of the 

 absence of one or more of the food-principles. 



27. The Potato. The common or Irish potato is the 

 vegetable most extensively used in this country and Great 

 Britain. Among the poorer classes in Ireland it is the 

 main article of food. While it is not so rich in nutritious 

 substances as many others, it has some very useful qualities. 

 It keeps well from season to season, and men do not weary 

 of its continuous use. It is more than two-thirds water, 

 the balance being chiefly starch, with a little albumen. 



28. The sweet potato differs from the white or common, 

 in containing more water and a small proportion of sugar. 

 The common potato and the tomato belong to the same 

 botanical order as the "nightshades," but do not possess 

 their poisonous qualities, unless we except potatoes that 

 are in the process of germination or sprouting, when they 

 are found injurious as food. 



29. Fruits. These are produced, in this country, in 

 great abundance, and are remarkable alike for their variety 

 and delicious flavor ; consequently they are consumed in 

 large quantities, especially during the warmer months. 

 The moderate use of ripe fruits, in their season, is 

 beneficial, because they offer a pleasant substitute for the 

 more concentrated diet that is used in cold weather. The 

 amount of solid nutriment they contain is, however, 

 small. The percentage of water in cherries is seventy- 

 five, in grapes eighty-one, in apples eighty two. Unripe 

 fruits contain starch, which, during the process of ripening, 



27. State what is said of the Irish potato ? 



28. Sweet potato ? Nightshades ? Potatoes when germinating? 



29. Fruits? Use of ripe fruit? Nutriment they contain? Starch in unripe 

 fruits ? Cooking of unripe fruits ? 



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