NUTEITION INVESTIGATIONS. 471 



The factors in the first, fourth, and seventh columns show what 

 proportion of the total protein, fats, and carbohydrates in the average 

 mixed diet is furnished by the food materials included in the different 

 groups indicated. Those in the second, fifth, and seventh columns 

 indicate the proportions of the different ingredients in the food 

 materials of the various groups that are digestible when eaten in 

 mixed diet. Those in the third, sixth, and ninth columns show how 

 much energy the body will derive from onevgram of each of the food 

 materials included in the different groups, while the last column in 

 the table shows what proportion of the total amount of energy in the 

 food materials of the different classes will be utilized by the body. 



With the exception of some important European determinations of 

 heats of combustion, the data on which these factors are based are from 

 late investigations in the United States. These include over 4,000 

 analyses of food materials; about 350 dietary studies; nearly 300 diges- 

 tion experiments, mostly with men; several thousand determinations 

 of heats of combustion of food materials and excretory products, and 

 30 experiments, continuing ninety-three days, with men in the respi- 

 ration calorimeter, besides a considerable number of other experi- 

 mental inquiries, including especially the determinations of the 

 constitution of protein compounds in various materials. The results 

 of computations by means of these factors have been found to agree 

 very closely with those obtained in actual experiments, showing that 

 the factors are reasonably accurate. 



THE EDUCATIONAL INFLUENCE OF THE NUTRITION INVESTI- 

 GATIONS. 



If the practical usefulness of these investigations is important, the 

 educational influence is no less so. This is manifesting itself in a 

 number of ways, but most of all in the bringing of the results of the 

 inquiry directly into schools. Taking all the public schools and col- 

 leges in the country together, the number in which the results of these 

 inquiries are being directly taught is relatively small. Nevertheless, 

 the actual number of institutions in which teachers are including more 

 or less of the outcome in their courses of instruction, especially in 

 physiology, is already large, and growing with most encouraging 

 rapidity. It has been the policy of the Department to deal very gen- 

 erously with schools and with teachers in the distribution of nutrition 

 publications. Not only in cities, but in rural districts the schools 

 manifest a large and rapidly growing demand for these publications. 

 They appear to meet an actual want — one that has been rather dimly 

 felt hitherto, but is now taking quite definite shape. The most active 

 call has been from teachers connected with technical schools or the 

 technical departments of colleges and high schools. That it has been 



