42 STUDIES IN PHYSIOLOGY 



Refuse. In many foods there are ingredients which the 

 body cannot use: for example, the hard part of bones, the 

 peel of potatoes, and the shells of eggs and of oysters. 

 These substances we call refuse. 



Explanation of Food Chart. 1 The folio wing chart (Fig. 13) 

 shows the percentage of each nutrient in several kinds of 

 food. The first line of figures at the top of the chart and 

 the vertical lines below them divide off the various per- 

 cents ; for example, 10%, 20%, 70%, etc. In preparing the 

 first line of the chart (which shows the composition of 

 round beef with bone) a large number of analyses of meat 

 were made and averaged. In each analysis a slice of round 

 beef with the bone was carefully weighed. The bone was 

 then removed, and found to constitute about 7% of the 

 original weight of the meat. This fact is shown 011 the 

 chart by the length of the black line representing refuse, 

 which extends from 93% to 100%. The meat itself was 

 then thoroughly dried to remove the water, and when the 

 residue was weighed, and the various analyses were com- 

 pared, it was found that water averages over 60% of this cut 

 of beef (represented on the chart by the double oblique lines 

 extending from about 33% to 93%). The proteids and fats 

 were separated by special methods, and the mineral matters 

 were obtained as ash by burning the beef. The chart then 

 shows that something over 19% of round beef consists of 

 proteids, about 12% is fat, and 1% more or less is mineral 

 matter.; while, as already noted, there is 60% of water, and 

 something over 7% of refuse and other indigestible matter. 



1 The United States Government has provided for an extensive in- 

 quiry into the food and nutrition of man. The work, done imder 

 the authority of the Department of Agriculture in Washington, has 

 been in charge of Professor W. O. Atwater of Wesley an University, 

 Middletown, Conn., in whose laboratory the enterprise was begun and 

 some of the most important part of the work has been done. The 

 practical results of this inquiry are published by the Department of 

 Agriculture* in the form of popular bulletins (see p. 60). Figures 13, 

 15, 16, 17, and 18 were copied from these publications. 



