NUTRITION 427 



(Front), and contains nitrogenous matter, oil, and sugar. Afterwards, experiments 

 were made to determine the amount of nitrogen in food, and the relative value of 

 nutriment was tabularly stated, in dependence on the ratio of nitrogen present in each 

 species (Boussingault, Ann. de Chim. Ixiii. 225, 1836), a method which has been super- 

 seded. It was subsequently inferred that nitrogenous matter supplied the waste of 

 the muscular tissue, while the non-nitrogenous constituents of the food served for 

 respiratory purposes, or the production of animal heat by obviating the too rapid 

 transformation of the muscular elements of the body (Liebig, Organische Chemie, 1842). 

 This was the true key to the solution of the problem as to the function of the nitro- 

 genous and non-nitrogenous food, and it laid open a wide field for enquiry in reference 

 to the applications of rational systems of dieting to the animal system. For example, 

 it was found in a series of experiments conducted for the British Government in 1845, 

 that in a stall-fed cow in one day, taken from an average of several months, the 

 amount of food conveyed into the circulation of the blood of the animal, was 14 '56 Ibs. 

 weight ; and when the nature of this mass of nutriment was subjected to chemical 

 inquiry, it appeared that T56 Ib. consisted of nitrogenous matter, and 13 Ibs. of non- 

 nitrogenous food. When the relation between these two quantities is calculated, it 

 results that the nitrogenous is to the non-nitrogenous food as 1 to 8'33, in the case of 

 an animal at rest. This observation led to researches into the relative constitution of 

 food as employed by different nations ; and the deduction was made, that it is a law 

 of nature that animals under the different conditions of rest and exertion, require food 

 in which the relation of the nutrient or nitrogenous food is different in reference to 

 the non-nitrogenous or heat-producing (calorifiant) constituent: that the animal 

 system may be viewed, as in an analogous condition to a field, from which different 

 crops extract different amounts of matter, which must be ascertained by experiment ; 

 an animal at rest consuming more calorifiant food, in relation to the nutritive con- 

 stituents, than an animal in full exercise. From the analyses then instituted the 

 following table was constructed : 



Approximate relation of nutritive or nitrogenous to calorifiant matter. 



Relation of Nutritive to 



Calorifiant Matter. 

 Milk food for a growing animal . . . . 1 to 2 



Beans . . . 1 2 



Peas \ 13 



Linseed J 



Scottish oatmeal 1 ., 5 



Wheat flour ) f 1 7 



InTanTorn Food for an animal at rest J to' 



Barley J L .."'.. 



Potatoes 1 9 



East Indian rice 1 10 



Dry Swedish turnips . . . . . . . 1 1 1 



Arrowroot ~j 



Tapioca }> 1 26 



Sago J 



Starch . 1 40 



These proportions will consequently vary considerably according to the richness 

 of the grain or crop, and hence similar tables which have been subsequently pub- 

 lished by others will be found to differ in some of the details from the preceding 

 data ; but the facts now stated' -given as approximate are probably as good averages 

 as could be selected. R. D. Thomson, ' Medico-Chirurgical Trans.,' xxix., and ' Ex- 

 perim. Researches on the Food of Animals,' 1846, p. 162. 



The Table on the following page is an illustration of the law of the equilibrium of 

 the food. 



The table is read thus: an English soldier consumes weekly 11,703 grammes (a 

 gramme equal to 15 '44 grains) of food. In this food 1,119 grammes are nitrogenous 

 or flesh-forming matter ; 3,937 non-nitrogenous or heat-producing material ; 152 mineral 

 substance ; the organic matter containing 2,219 grammes carbon. The relation of the 

 nitrogenous to the non-nitrogenous matter is as 1 to 3 '50. From this table the results 

 have been deduced that soldiers and sailors consuming 35 ounces of nitrogenous or 

 flesh-forming food weekly, and 70 to 74 ounces of carbon, the proportion of the carbon 

 in the flesh-forming, to that in the respiratory or heat-forming food, is as one to three. 

 Older persons require only 25 to 30 flesh-forming matter weekly, and from 72 to 78 

 respiratory food ; the relation of the carbon in these is as 1 to 5. Boys of from ten 



