COMPOSITION OF FOODS. 



357 



2. Inorganic substances or Salts are an integral part of all tissues, and without 

 them the tissues cannot be formed. They occur in ordinary food. The addition 

 of too much salt increases the consumption of water, and this in turn increases the 

 transformation of N in the body. If an animal be deprived of salts, nutrition is 

 interfered with ; food deprived of its lime affects the formation of the bones ; de- 

 prival of common salt causes albuminuria (247, A, III). The alkaline salts serve 

 to neutralise the sulphuric acid formed by the oxidation of the sulphur of the pro- 

 teids. Iron, which is so essential for the formation of blood, exists in animals and 

 plants in combination with complex organic bodies. 



Only in times of famine is man driven to eat large quantities of inorganic substances, to 

 extract the organic matter mixed therewith. A. v. Humboldt states, in regard to the inhabit- 

 ants of the Orinocco, that they eat a kind of earth which contains innumerable infusoria. 



3. At least one animal or vegetable albuminous body or proteid ( 248, 250). 

 The proteids are required to replace the used-up nitrogenous tissues, e.g., for 

 muscles. They contain 15*4 to 16*5 per cent. X. 



The proteids are in blood -=20*56 percent.; muscles, 19*9 per cent; liver, 11'74 percent.; 

 brain, 8 '63 per cent.; blood-plasma, 7 '5 per cent.; milk, 3*94 per cent.; lymph, 2*46 per cent. 

 According to Pfliiger and Bohland, a youth of full stature, and 62 kilos. [136 lbs.] weight, de- 

 composes 89*9 grms. of albumin daily. 



Asparagin, in combination with gelatin, can replace albumin in the food ( JVeiske), while 

 asparagin alone limits the decomposition of albumin in herbivora but not in carnivora (/. Munk). 

 Ammoniacal salts, glycocoll, sarkosin, and benzamid increase with the amount of albumin in 

 the body. 



4. At least one fat ( 251), or a digestible carbohydrate ( 252). These chiefly 

 serve to replace the transformed fats and non-nitrogenous constituents. Owing to 

 the large amount of C wdiicli they contain, when they undergo oxidation, they form 

 the chief source of the heat of the body ( 206). Fats and carbohydrates may 

 replace each other in the food, and in inverse proportion too, corresponding to 

 the amount of C which each contains. As far as the mere evolution' of heat is 

 concerned, 100 parts of fat = 256 of grape-sugar = 234 of cane-sugar = 221 of dry 

 starch (Buhner). A man consumes 210 grms. fat daily. 



[5. Every proper diet ought to have a'certain degree of sapidity or flavour. The substances 

 which give this are not useful in the evolution of energy or building up the tissues, but they 

 stimulate the nervous system and excite secretion. They are called " Genussmittel " (means 

 of enjoying food) by the Germans, but we have no exact equivalent for this word in English, 

 though the articles themselves are included under our expression "condiments." These sub- 

 stances are the aromatic matter in roast meat (osmasome), tea, vinegar, salt, mustard, pepper, 

 &c] 



[Condition of Diet for Health. In an adequate diet, not only (1) should the 

 total quantity be sufficient and not more than sufficient, but (2) the constituents 

 should exist in proper proportions, (3) be digestible, and (4) the whole should be in 

 good condition, wholesome, and not adulterated with any substance prejudicial to 

 health.] 



With regard to the relative proportions of the various kinds of food which 

 ought to be taken, experience has shown that the diet best suited for the body 

 must contain 1 part of nitrogenous foods to 3 J or, at most, 4 J of the non-nitro- 

 genous. Looking at ordinary foods from this point of view, we see how far they 

 correspond to this requirement, and how several substances may be combined to 

 produce a satisfactory diet. 



1. Veal, 



2. Hare's flesh, 



3. Beef, 



4. Lentils, . 



5. Beans, 



6. Peas, 



7. Mutton, . 



Xit. Xon-Xit.' 



8. Pork, . . 10 30 



9. Cow's milk, 10 30 



10. Human milk, 10 37 



11. Wheaten 



flour, . 10 46 



12. Oat-meal, . 10 50 



13. Rye-meal, . 10 57 



Xit. Xon-Xit. 



14. Barley-meal, 10 57 



15. White 



potatoes, 10 86 



16. Blue ,, . 10 115 



17. Rice, . . 10 123 



18. Buckwheat- 



meal, .. 10 130 



