THE PKOTEIN REQUIREMENTS OF MANKIND 119 



of the University ; some were athletic in build and tendencies, 

 others slender, and inclined to take little physical exercise. 

 The twenty-four hours' urine was collected, and the total amount 

 of metabolized nitrogen determined, the subject taking his usual 

 amount and character of food. One hundred and eight persons 

 were so studied. The following are the points elucidated : 



Chittenden draws the conclusion from these results that the 

 108 individuals selected at random from a large group of men 

 were plainly taking a very much smaller amount of protein food 

 than is generally considered essential for good health. 



These men were apparently strong, healthy individuals, some 

 of them indulging in vigorous athletic work, while as a group 

 they represent the average type of vigorous manhood common 

 to most University centres. He asks the question : " Are we to 

 assume that this large group of men, taking on an average only 

 80 per cent, of the amount of protein food generally considered 

 essential for health, were all in danger of nitrogen starvation ? 

 Certainly, if the Voit standard of 118 grammes of protein food 

 represents the limit below which it is not safe for the average 

 man to drop ; then these individuals were living at a dangerously 

 low level of nitrogen intake. Are we to assume that all these 

 young men were unconsciously undermining their health, gradu- 

 ally destroying their vitality, and paving the way for the en- 

 croachment of disease through faulty habits of life." 



We have quoted sufficiently from this interesting paper to show 

 the line of argument adopted, but there are several points that 

 appear to call for adverse criticism. These we shall deal with at 

 once, reserving the consideration of Chittenden's results obtained 

 from his three groups of subjects for the succeeding chapter. 



1 . Chittenden relies entirely on the nitrogen excreted in the 

 urine as a measure of the nitrogenous metabolism ; this is not 

 an accurate method. Under conditions where the diet is uniform 

 and does not vary from day to day, the average excretion of 

 nitrogen in the urine over long periods may approximate closely 



