12 Metabolism of Healthy Man. 



experimenting has been seriously questioned. There may be a distinct interval 

 elapsing between the disintegration of protein and the elimination of nitrogen, 

 and, indeed, the excretion of carbon dioxide resulting from such disintegration. 

 Protein katabolism and nitrogen balances are subjects which can be dealt 

 with outside of and independent of a respiration calorimeter. The large amount 

 of chemical analysis and routine work involved in a series of experiments as 

 extensive as is this, made it practically impossible to simultaneously engage 

 in a long study of the nitrogen metabolism. Furthermore, it seemed more 

 desirable to obtain results on a relatively large number of subjects than to 

 make duplicate experiments or a large number of experiments with the same 

 subject. Obviously, the difficulties attending the prescription of a preceding 

 diet and obtaining rigid adherence thereto for several days before an experi- 

 ment made such preliminary supervision impracticable. The experiments 

 presented in this report, therefore, do not purport in any way to throw light 

 upon the normal nitrogen metabolism of man, and but few figures are given 

 with regard to the urinary analyses. We have to deal here chiefly with the 

 gross metabolism as indicated by the vaporization of water, carbon-dioxide 

 production, oxygen absorption, and heat elimination and production. 



