334 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, the diet A 

 being that already quoted in 527 : 



A B 



Proteids 10.0 grms. 118 



Fats 100 56 



Carbohydrates 240 500 



Salts 25 



Water 2600 



The total (available) potential energy is respectively 2310, and 

 3035 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 

 1 normal ' one, and that is the one which we employed in the calcula- 

 tions of 527. It will be observed that the potential energy of 

 this diet is less than that of any of the others, and, as we said 

 while then speaking of it, may be considered low ; but there 

 was no evidence that it was insufficient. Still it must be remem- 

 bered 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 main- 

 tain 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 observations have been made 

 tending to shew that a man of average size and weight may 

 continue in nitrogenous equilibrium and in good health with a 



