642 



MISCELLANEOUS FARM SUBJECTS 



food habits, it would have been difficult to secure a sufficient amount 

 of nitrogen-free material without a correspondingly large amount of 

 protein. 



The quantity of protein actually required by the body is a very 

 important matter, and a question which is as yet by no means solved. 

 Dietary standards should be in reasonable harmony with physiolog- 

 ical demands, and it seems probable that such is the case with those 

 which have been most generally used. That this is true of energy 

 can be shown by the experiments which have been made with the 

 respiration calorimeter in connection with the nutrition investiga- 

 tions of the Office of Experiment Stations. 



MINERAL MATTER REQUIRED IN THE DIET. 



To be most useful, dietary standards should take into account 

 the amount of ash constituents required by the body, for it is well 

 known that mineral matters of different sorts are essential for use in 

 forming bones and other body tissues for the repair of the body and 

 for other purposes. Many general statements are met with regard- 

 ing the great importance of mineral matter, and many theories of 

 nutrition have been based to a large extent on mineral constituents. 

 Experimental investigations, particularly physiological studies along 

 these lines, are not very numerous. A recent estimate of the min- 

 eral matter required per man per day calls for the following 

 amounts : 



Estimated Amount of Mineral Matter Required Per Man Per Day. 



GRAMS. 



Phosphoric acid (PaO) 3-4 



Sulphuric acid (SOs) 2-3.5 



Potassium oxid 2-3 



Sodium oxid 4-6 



GRAMS. 



Calcium oxid 0.7 -1.0 



Magnesium oxid 0.3 -0.5 



Iron 0.006-0.012 



Chlorin 6 -8 



Silica, iodin, fluorin, are required in smaller amounts. With 

 ordinary mixed diet the needs of the body for mineral matter are 

 usually supplied. 



Under the Preparation of Food a table is given showing what 

 minerals are furnished by common foods. As a rule the American 

 diet is sufficient for all needs except perhaps in some cases of ex- 

 treme poverty or ignorance and bad management. 



A special phase of the question which has recently received 

 much attention is that of underfeeding among the children in the 

 public schools. There seems little doubt that many children in the 

 congested sections of American cities are decidedly undernourished, 

 though this condition seems less widespread than in some European 

 cities. Wherever it exists this underfeeding is an important factor 

 in the arrested physical and mental development and also in the 

 tuberculosis and other diseases which are so prevalent in such con- 

 gested centers. It is not only that many parents can not provide 

 sufficient food for their children, but also that they frequently pro- 

 vide the wrong food, or give the children pennies with which to buy 



