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evident, assuming as before that 85 per cent. of the protein of rice is absorbed so
long as the quantity of rice does not exceed a certain amount, that if we increase
the quantity of rice beyond this amount, even if a smaller percentage of the
protein is absorbed, the now greater quantity of protein from the increased amount
of rice multiplied by a slightly diminished co-efficient of absorption will give an
actually greater quantity of protein undergoing metabolism in the body. This
will hold true up to a certain limit and when this is passed, the actual amount of
protein undergoing metabolism will diminish instead of increasing as more and
more rice is added to the diet. An illustration will make this line of reasoning
clear:—

     Supposing 5 grammes of nitrogen in the form of rice to be the maximum
         amount from which full absorption takes place, then 5 X 0.85 =
         4.25 grammes is the amount of nitrogen undergoing metabolism.

    Now assume that for every increase of 1 gramme of nitrogen in the form of
rice there is a fall of 10 per cent. in the co-efficient of absorption then:—

so that we obtain the maximum absorption in our illustration with 7 grammes,
and the amount of rice present in the diet from which this maximum absorption
takes place we may call the optimum amount; of course, it is understood that all
other constituents of the diets remain constant.

    Basing our investigations on this principle we have worked out the optima
amounts of the different food-stuffs made use of in the dietaries of Lower Bengal
and Behar, and plotted our results out in. the form of curves of absorption under
varying quantities of each different food material whilst all other constituents are
kept constant. It will be readily admitted that, having found the particular
quantities of the different food-stuffs from which the greatest amount of protein
is absorbed, we have got the particular quantity of each food-stuff that is the most
useful to the body, and, therefore, the most economical so far as that type of diet
is concerned; and, by combining those quantities of the food-stuffs available in
Bengal and Behar, we get diet scales based on the real nutritive value of the foods
of the country. It will be evident that investigations carried out on this plan
entailed an immense amount of work as compared with the simpler methods in use
in Europe and America. Instead of our being able in a few experiments to obtain
the nutritive value of a "basal diet" and then add rice, wheat ata, different dais
or makkai ata to it, and calculate from the percentage of the extra amount
absorbed the co-efficient of protein absorption for each food-stuff, for every
food-stuff a whole series of experiments had to be carried out to obtain its curve
of absorption under varying conditions.