— 8 — 



non-nitrogcnous materials; others, as the potato, rice, and some friiits, 

 have chiefly starchy matter associated with small quantities of albu- 

 minoids; and again, as in the case of the vegetahles in general, we have 

 small amounts of both carbohydrates and nitrogenous materials. 



The Proportion between the two important elements of our food is 

 termed the nutritive ratio; or, in other words, it is the ratio of the 

 digestible protein to the sum of the digestible portions of the remaining 

 ingredients of the food. In estimating this remainder, the figiire denot- 

 ing the amount of fat is multiplied by 2.25, because it has been ascer- 

 tained by experiment, as before stated, that about 2.25 times as much 

 heat is developed by the combustion of a pound of fat as is by the same 

 quantity of carbohydrates. This product is added to the weight of the 

 carbohydrates and the sum divided by the figure for the protein, the 

 quotient being the nutritive ratio. 



To illustrate, let us take wheat flour, the analysis of which is as fol- 

 lows: Water, 12.50 per Cent; protein, 8.00 per Cent; fat, 1.10 per cent: and 

 carbohydrates, 77.90 per cent. The fat percentage, 1.10, multiplied ])y 

 2.25, amounts to 2.48; this added to the figure for the carbohydrates, 

 77.90, makes 80.38, which divided by 8, the per cent of protein, gives 

 10.05. Hence, the nutritive ratio is 1:10; in other words, there is in 

 wheat flour one part of protein or nitrogenous matter to 10 parts of non- 

 nitrogenous or starchy material. The ratio is " wide," and termed a car- 

 bonaceous one when the amount of protein to the remaining ingredients 

 is small, as seen above. A "narrow" or nitrogenous ratio is one where 

 the reverse is the case; that is, the amount of protein is large compared 

 to that of the carbohydrates: as 1 of protein to about 4 or 5 of sugar or 

 starchy matters. 



DIETARIES. 



When speaking of cattle foods, the amount which is daily necessary 

 to keep an animal in a healthy, satisfied condition is a ration. In dis- 

 cussing human foods, the quantity required for daily consumption is 

 termed a dietary, although both terms are in use. A well-balanced diet 

 is one in wliieh the protein, or flesh-formers, and carbohydrates, or fat- 

 producers, exist in ihv proper proportion. Usually we use foods or diets 

 unbalanced, in that they contaiu too much (■arbt)hydrates. In other 

 words, we eat too much starch and fatty foods and an insufficient 

 amount of nitrogenous or flesh-forming ingredients. 



The dietary Standards at our command have been worked out liy \'oit 

 in Cierniany, Playfair in England, Atwater in the Uniteil States, and 

 others. The daily average for the (lifiVi-cnt ingredients is altout one 

 quarter pound of protein, a third of a jtomul of fat, and a little over a 

 pound of carbohydrates, making a nutritive ratio of 1:5.8, with a fuel 

 value of about ;'>,5()() cal(U'ies. 



Fiiel ]'alue.- By having the analyses of tlie dilTerent foods at our dis- 

 posal, we would be able to calculate a considerable nuinl)er of dietaries; 

 l)Ut a somewhat simi)ler method is to use what is ternieil the fuel 

 value of foods. Tliis, as the namc im])1ies, is the lieating power of the 

 food. If we l»urn a ])ie('e of fat it will giMierate a certnin amount of 

 lieat, so will a lump of sugar or starcli, or any other food-niaterial. 

 If this heat wore applied to water, it wouhl warm it to a greater or less 

 extent, <h']»cii(ling U])on Ihc niiiounl ol" heat sd free by the coiuhustion 



