



DIGHSTIBILITY OF CEREAL BREAKFAST FOODS. 187 
composition and heats of combustion of the materials are given 
in the following table. It will be observed that the figures for 
the feces are those for the material in the partially dried condi- 
tion in which it was analyzed. Inasmuch as the total quantity 
of water in the feces is not considered in a digestion experiment, 
it seemed unnecessary to reduce the figures from those for the 
partially dried to those for the fresh material, since the calcula- 
tion of the ingredients in the feces may be made in the same 
way, by use of the figures here given, and the total weight of 
partially dried feces. 
CALCULATION OF RESULTS. 
The data of the digestion experiments are given in Tables 
84 to 86 beyond. ‘The first column in each table shows the 
total quantity of each food material consumed, and of feces 
excreted (except that the weight of feces is that of partially 
dried rather than fresh material), and the third and succeeding 
columns the quantities of nutrients and energy contained in the 
food and feces as calculated from the figures in the first column 
and those in Table 82. Thesecond column shows the quantity 
of total organic matter in the food and the feces, as found by 
adding the quantities of protein, fats and carbohydrates. From 
the figures for the quantity of each nutrient in the food and 
in the feces the digestibility or availability of the nutrients in 
the total diet and in the cereal portion alone are computed, 
according to the method here described. 
Digestibility or availability of total diet.—In. the case of the 
diet as a whole, the computation of what is commonly consid- 
ered the digestibility of the nutrients is a comparatively simple 
matter. The difference between the quantity of each nutrient 
in the total food and the amount of the corresponding ingredient 
in the feces is taken as the quantity of the given nutrient di- 
mested. -- Dividing the amount digested by the total amount in 
the food eaten, and multiplying by 100, gives the percentage 
of the given nutrient digested; or, as it is generally called, its 
coefficient of digestibility. - 
Strictly speaking, the results thus obtained do not represent 
actual or true digestibility, for the reason that the feces contain 
not only the portions of food that are not digested, but also 
