O'SEIEA — ASPECTS OF MENTAL ECONOMY. 



83 



of calculation, since the element of life in general and individu- 

 ality in particular/ which cannot be precisely reckoned with in 

 our present methods of scientific experiment, probably modify 

 in some measure the value of a food as it might appear when 

 subjected to chemical examination. But chemical analysis can 

 ascertain with accuracy the composition of any food, and this 

 has been relied upon for a long time as a measurably safe index 

 to the worth of any article. It is certainly not an overstatement 

 to say that it is a reasonably reliable and serviceable method of 

 determination. Granting an unknown and indeterminable fac- 

 tor in estimating the nutritive value of any food, yet chemical 

 analysis would enable us to say this much at least, — that there 

 are certain things in which it would be impossible, considering 

 the limitations of the human digestive apparatus, to get sufficient 

 albuminous elements, for instance, to support active, vigorous 

 life ; while in others, if eaten exclusively or even largely, albu- 

 men would be gained in excess. In this way, though the for- 

 mulas obtained from chemical analyses do not represent the 

 exact value of milk, for instance, as it will be received by the 

 stomachs of different persons, yet, to repeat, it does indicate the 

 substances from which the several elements may be derived most 

 easily and economically, and this will give enough play to in- 

 dividual preferences and idiosyncrasies in digestion and assimi- 

 lation. It should be said, too, that while the organism requires 

 a certain quantity of fats, carbohydrates, and albumen, yet the 

 administration of these in pure form would not serve to properly 

 nourish a person. The nutrition which they contain is yielded 

 only when they are obtained in an organized state as they are 

 found in nature in the fruits, seeds, etc., of plants and in the 

 flesh of animals. 



The composition of foods as given by various investigators, 

 while differing in some cases in slight degree, are yet for all 

 practical purposes identical. The most satisfactory analyses 



i Charts showing differences between individuals in digestive characteristics, 

 for instance, are shown further along, in Chap. VI. 



