178 
generally believed. Of the three classes of organic constituents, 
all are doubtless more or less interchangeable as to their effects, 
yet the non-nitrogenized are in general regarded as fat-makers 
and they contribute most of the carbon which is consumed by 
oxidation. They are therefore known as the carbonaceous or 
respiratory foods, or fat-formers. They comprise two classes, 
the fats or fixed oils and the carbohydrates, which latter the 
system is capable of converting into fat. Of the latter, the more 
important are sugar, of which there are several varieties, differing 
markedly in their digestive and nutritive properties, and starch, 
all forms of which are practically identical in this respect. Inu- 
lin is a substance very closely related to sugar, the nutritive 
properties of which have received practically no attention. There 
are good reasons to believe them very valuable. Those familiar 
with the delicious qualities of either the Jerusalem or the globe 
artichoke, or of salsify, have some acquaintance with inulin. 
Pure cellulose is also a carbohydrate nutrient when in a condition 
available to the digestive functions, but it is usually not so. All . 
those substances, as stated, are readily convertible by digestion 
and assimilation into fat. This fat, if not required, is stored as a 
reserve food (besides sustaining numerous other uses) for a 
longer or shorter period and then consumed. Obviously, the 
re) 
2 
ydrates, which require such conversion, and practical 
physiologists have reckoned it as 2,4 times as valuable. There- 
fore, if the percentage of fat in a food be multiplied by 2.4 and 
the product added to the total carbohydrates, it gives us the 
total value, in carbohydrate units, of the carbonaceous, respi- 
ratory or fat-forming nutrients of that food. The ratio which 
this sum bears to the albuminoids, that is, the number of carbo- 
hydrate units for each albuminoid unit, constitutes what is called 
the nutritive ratio of the food. The method is fully illustrated 
in the following table of the more important foods and fodders 
of the bean family, the foods of which possess the highest nutritive 
ratios : 
