874 THE NORMAL DIET. [BOOK n. 



in nitrogenous equilibrium with the nitrogen of the egesta equal 

 to that of the ingesta. To make sure that under such a diet the 

 body was remaining of the same composition there ought to be 

 evidence of a carbon equilibrium also, otherwise during the period 

 of the experiment fat might be being replaced by water (see 

 521); but this is unlikely, and we may therefore accept the 

 method as a fair one. It has given in the hands of two different 

 observers the following somewhat different results, already quoted 

 in 527 : 



A B 



Proteids 100 grms. 118 



Fats 100 56 



Carbohydrates 240 500 



Salts 25 



Water 2600 



The total (available) potential energy is respectively 2360, and 

 3063 calories. 



On the whole the diets gained by the two methods agree very 

 largely. To put down a single column of figures as " the normal 

 diet " would be to affect a vain and delusive accuracy. If we desire, 

 for theoretical purposes, to select some one set of figures rather 

 than others, we might be influenced by the considerations that 

 the lower amount of proteids in the experimental diet was nearer 

 the mark than the higher amount of some of the statistical diets, and 

 further that, where cost is not of moment, the substitution of fat 

 for an excess of carbohydrates is desirable. We should be thus led 

 to take the experimental diet A as on the whole the best or most 

 ' normal ' one. It will be observed that the potential energy of 

 this diet is less than that of B, and indeed of most of the others, 

 and may be considered low; but there was no. evidence that 

 it was insufficient. Still it must be remembered that neither 

 it nor any of the others is to be regarded as distinctly proved 

 to be the real normal diet. Against the experimental diet we 

 may urge that the number of experiments have been few and 

 conducted on a few individuals only at most, and that a larger 

 number of experiments, with a variety of combinations of different 

 amounts of the several food-stuffs, might lead to a different result; 

 that for instance with certain amounts of fats and carbohydrates, 

 the amount of proteid needed to maintain healthy bodily equilibrium, 

 including nitrogenous equilibrium, might be reduced much below 

 the 100 grammes, especially if particular kinds of proteids, fat or 

 carbohydrates were used, and especial attention (see 526) were 

 paid to the salts. And indeed a considerable number of observa- 

 tions have been made tending to shew that a man of average size 

 and weight may continue in nitrogenous equilibrium and in good 

 health, for some time at least, with a daily ration of much less 

 than 100 grm. proteid, with as little as 40 grm. for example. To 



