VALUE OF DIFFERENT FOODS. 569 



peculiarities of diet, and also the fact that, as a rule, a foreign dietary, 

 unless modified, or gradually adopted, is less adapted to the digestive 

 powers of individuals of different nations and climates. 



Finally, the effects of individual differences, or, as they are called, 

 idiosyncrasies, are truly remarkable in the case of the digestive func- 

 tions. In certain instances, particular, and perhaps not otherwise 

 difficultly digestible, substances invariably produce the most serious 

 pain and disorder ; whilst substances ordinarily indigestible, may per- 

 haps be readily digested. Thus, for example, oysters, lobsters, crabs, 

 and salmon, will each produce, in different persons, severe attacks of 

 indigestion, and even give rise to eruptions on the skin. In some 

 persons, strawberries are known to produce a similar effect ; and to 

 others, cucumber is almost a certain poison. 



Relative Value of Different Foods. 



The following Table, chiefly from Vierordt, exhibits the composition 

 of a few of the great variety of articles of food consumed by Man. 

 It shows the total amount of solids, and the proportions of organic 

 proximate constituents, salts, and water, in each article of diet ; also 

 the relative amount of its nitrogenous and non-nitrogenous constituents, 

 and, as regards the latter, the respective quantities of oleaginous, 

 amylaceous, and saccharine matters. The relative value of different 

 articles of diet, for plastic or tissue-forming purposes, for calorific or 

 respiratory purposes, or for maintaining the proper saline constitution 

 of the blood, is thus shown, so far as their chemical composition is con- 

 cerned ; but this alone affords no sufficient indication for the practical 

 choice of diet in individual cases, so much depending on the physical 

 characters and mode of preparation of food, as well as on the age and 

 idiosyncrasies of the individual. 



The total quantity of solids, shown in the first column of the fol- 

 lowing Table, reveals the highly nutritive quality of leguminous and 

 cereal food, butter, cheese, and eggs, in comparison with meat ; but 

 such general comparisons are inexact, for the proportions of non-nitro- 

 genous and nitrogenous substances, in each kind of food, are not taken 

 into account. As regards the latter, cheese is the most nutritious diet, 

 then the leguminous seeds, next meat, and then, in order, the yolk of 

 egg, flour, the white of egg, and bread. As regards fat, the order of 

 nutritive value is, butter, yolk of egg, and cheese. Starch and sugar 

 are most abundant in wheat, next in the leguminosa and the inferior 

 cereals, less so in potatoes, and least in the succulent vegetables and 

 fruits. 



Cheese is an extraordinarily concentrated diet ; the leguminosa are 

 highly nutritious, especially those grown in hot countries, but they 

 require a thorough preparation and good cooking ; the great merit of 

 bread is its soft, porous, permeable, and well-cooked substance ; the 

 advantage of meat consists in its concentrated, yet succulent, tender, 

 and easily digested substance, and in its containing the very elements 

 of the tissues and the blood, even fat, creatin, and the potash salts. 

 Potatoes are a weak food, one pound being only equal to about six 



