368 



REPORT OF OFFICE OF EXPERIMEIS'T STATIONS. 



calculated by the use of factors. The following table shows the 

 factors for calculating the digestibility and fuel value of nutrients in 

 a number of single foods and groups of food materials, which have 

 been deduced from the large number of digestion experiments carried 

 on in connection with the nutrition investigations of the Office. A 

 comparison of calculated results with data obtained from natural 

 digestion experiments has shown that these factors are reasonably 

 accurate, and it seems fau' to say that they are more satisfactory 

 than any which have been hitherto proposed. 



Factors for calculating digestibility and fuel value of nutrients in food materials. 



The table shows that the cUfferent food materials and groups of food 

 materials vary greatly in the thoroughness with which they are assim- 

 ilated. Meats of different sorts, as ordinarily prepared for the table, 

 and indeed animal foods as a whole, are more completely digested 

 than the common vegetable foods. Considering foods as a whole, 

 96 per cent of the total organic material is digested and 91 per cent of 

 the energy is available. In other words, on an average the body 

 rejects only about 4 per cent of the nutrients and about 9 per cent of 

 the energy supplied by the food. 



RESPIRATION CALORIMETER EXPERIMENTS. 



In conducting oxi^erimcnts of various kinds it is often very desirable 

 to know every re(|uirement of a subject engaged in muscular work. 

 The exact measurement of energy expenditure is time consuming and 

 requires special apparatus, but with tli(> aid of the factors deduced 

 from the large number of experiments which have been made with 



