1905-6.] Miss I. D. Cameron on A Dietary Study. 
329 
can be maintained on one-third the usual proteid allowance, 
then the additional proteid adds enormously to the wear and 
tear of the tissues. It is an incubus instead of a help in the 
bodily economy. 
The discussion of the amount of proteid required by young 
tissues is not touched by Chittenden. It is reasonable to suppose 
that more proteid is required during growth, as proteid is the 
“ muscle-builder.” The power of resistance shown during a 
long, exhausting disease by tissues nourished for a considerable 
time on a low proteid intake is also a point of interest. 
Chittenden’s work does not enter on these points, and was not 
intended to do so. 
The influence of this recent work on proteid requirements is 
seen in the Report of the Departmental Committee on Vagrancy, 
issued this year. The daily food allowance for casual wards and 
labour colonies is 70 grammes of proteid, while the total energy 
value of the diet is 3000 calories. The ration may, however, be 
supplemented from pocket-money given for industry. 
So far, the history of the present dietary standards (expressed as 
proteids, fats, and carbohydrates) has been considered ; and by 
what methods — at first empirical and later experimental — they 
have been arrived at. But other standards may be used. The 
food required may be stated in terms of the contained nitrogen 
and carbon. 
The energy value expressed as heat also serves as an important 
standard. Lavoisier showed that the final change in the food in the 
body was a process of oxidation. Frankland decomposed different 
articles of food, and estimated the amount of heat liberated in the 
process of disintegration. The unit employed is the Calorie, i.e. 
the amount of heat required to raise 1 kilogramme of water 1 
degree Centigrade. In estimating the heat value of proteid, it is 
necessary to remember that the final product of its metabolism is 
urea, and allowance must be made for this incomplete oxidation. 
Riibner * has estimated that 1 gramme of proteid gives on 
combustion 4T Calories ; 1 gramme of carbohydrate also gives 
4'1 ; while 1 gramme of fat yields 9 '3 Calories. Taking into 
consideration more accurate chemical analyses and more recent 
* Zeitscbr. f. Biol., xxi. (1885), p. 337. 
