90 BULLETIN OF THE UNIVERSITY OF WISCONSIN. 



manufacture by the application of heat in the first case and by 

 malting in the second, which convert it into certain varieties 

 of dextrin, a point which will be considered more fully later 

 in discussing the modes of preparing food. This predigestion 

 of the starch renders such foods much more palatable and de- 

 licious than the ordinary uncooked article. It may be remarked 

 here, too, that in view of the fact that the ease with which a 

 food can be made to yield the energy it contains is perhaps 

 the most important factor in the determination of its nutritive 

 value, at least for one engaged in mental labor, it can be seen 

 that the foods just mentioned are far superior to those generally 

 found in the dietary lists of our students. 



§5. The Nutrient Value of Student's Dietaries, — Estimates 

 and Comments. — What now about the dietaries submitted in re- 

 sponse to our questionaire ? In order to determine their value 

 in a complete and scientific manner one should have ascertained 

 the precise quantity of each dish eaten, its exact composition, 

 and the digestive peculiarities of each individual ; and these data 

 could be obtained only with great difficulty, if indeed they could 

 be secured at all. But (and this has been said already) there 

 was at the outset no intention of making an elaborate and de- 

 tailed study of local conditions, so that the facts in hand are suffi- 

 cient to warrant the general suggestions which will be offered. 

 In estimating the value of a dietary one must know, in the first 

 place, how much energy a person could profitably expend in his 

 daily activities and what amount >and variety of food is neces- 

 sary to supply this. It has been calculated that a man engaged 

 in active muscular work expends energy equal to about 150,000 

 metre-kilograms or 4,000 calories, a calorie representing the 

 amount of heat required to raise one gram one degree Centi- 

 grade. 1 While it has not been possible, so far as I know, to de- 

 termine the precise amount of energy expended by >a student en- 

 gaged in severe mental labor, yet one is warranted in assuming 

 that it is not far below that indicated for a man employed in 

 muscular pursuits, 2 and it is not incredible that it should be 

 greater. 



1 Stevenson & Murphy, Treatise on Hygiene, Vol. I, p. 401. 



2 See, for instance, Sargent, North American Review, May, 1897. 



