ON DIET. 523 



very doubtful whether we ever, even in supreme efforts, draw upon more 

 than a portion of the capital of energy lodged in the muscle itself; fatigue 

 is far more a nervous than a muscular condition, and even the distinctly 

 muscular fatigue is as we have seen ( 86), partly at least the result of the 

 accumulation of products and not alone the using up of available energy. 

 In choosing a diet for muscular labor we must have in view not the muscle 

 itself but the whole organism. And though it is possible that future research 

 may suggest minor changes in the various components of a normal diet such 

 as would lessen the strain during labor on this or that part of the body, on 

 the muscles as well as on other organs, our present knowledge would rather 

 lead us to conclude that what is good for the organism in comparative rest 

 is good also for the organism in arduous work, that the diet, normal for the 

 former condition, would need for the latter a limited total increase but no 

 striking change in its composition. In preparing the body for some com- 

 ing arduous labor, in " training," as it is called, an increase of proteid food, 

 for the purpose of hurrying on the general metabolism of the body, and 

 thus of making " new flesh " and renovating the body, so to speak, in view 

 of the strain to be put upon it, may perhaps suggest itself; but even this is 

 doubtful. 



The principles of such a conclusion with regard to muscular work may 

 be applied with still greater confidence to nervous or mental work. The 

 actual expenditure of energy in nervous work is relatively small, but the 

 indirect influence on the economy is very great. The closeness and intri- 

 cacies of the ties which bind all parts of the body together are very clearly 

 shown by the well-known tendencies of so-called brain work to derange the 

 digestive and metabolic activities of the body ; and if there be any diet 

 especially suited for intellectual labor it is one directed not in any way 

 toward the brain, but entirely toward lightening the labors of and smoothing 

 the way for such parts of the body as the stomach and the liver. 



