186 STORRS AGRICULTURAL EXPERIMENT STATION. 
THE DIGESTIBILITY OF DIFFERENT CLASSES OF 
FOOD MATERIALS. 

BY W. O. ATWATER. 

In a discussion of the results of digestion experiments 
accompanying a compilation* prepared by the writer with the 
cooperation of Dr. C. Ford Langworthy, an attempt was made 
to summarize the results of the experiments made up to the 
time of the compilation (1895). ‘The estimates for coefficients 
of digestibility, which were almost identical with those given 
on page 175 of the Report of this Station for 1892, were as 
follows: Animal foods: protein, roo} per cent.; fats, 95-98 per 
cent.; carbohydrates, 100 per cent. Vegetable foods: protein, 
75-857 per cent.; fats, 95 per cent.; carbohydrates, 95 per cent. 
Starting with these coefficients as a basis, food materials 
were divided into three general classes: 1. Animal foods, in- 
cluding meats, fish, eggs and dairy products. 2. Cereals and 
sugars, including the flours and meals from cereal grains, 
bakery products, starches and sugars. 3. Vegetables, in- 
cluding beans, peas and other leguminous seeds, and fruits. 
Coefficients of digestibility were assumed for the protein, 
fats and carbohydrates of each of the three classes. ‘hese 
coefficients were applied to the different classes of food mate- 
rials used in some actual digestion experiment with a mixed 
diet. If the results obtained by the two methods, namely, by 
calculation and by experimental determination, agree closely, 
the agreement may be taken as indicating that the coefficients 
are approximately correct. While such a computation is not a 
complete mathematical demonstration, if the agreement is very 
close it may be regarded as sufficiently accurate for practical 
purposes. | , 
” * Bulletin No, 21 of the Office of Experiment Stations of the United States Depart- 
ment of Agriculture, On Methods and Results of Investigations on the Chenuistry and 
Economy of Food, p. 70. The figures are practically the same as had been previously 
given by the writer as the outcome of a less extensive compilation, Century Magazine, 
September, 1887. 
+ These figures assume that the nitrogenous metabolic products of the feces belong 
to the digested protein. 

