802 



PHYSIOLOGY 



TABLES I AND II 

 DISTRIBUTION OF NITROGEN IN URINE ON VARIOUS DIETS 



of nitrogen appearing as urea is reduced to 60. On the other hand, practi- 

 cally identical amounts of creatinine are obtained undei the two conditions, 

 so that whereas on the full diet it amounts only to 3-6 per cent., on the low 

 protein diet it forms as much as 17 per cent, of the total nitrogen output. 



4 8 12 16 20 24Hours 



FIG. 364. The hourly variation in the excretion of nitrogen after a meal. 

 The meal was given at 0. The thick line represents the average ab- 

 sorption of the food from the alimentary canal. The thin-lined cun 

 represent the N. excretion (1) after a meal of 1000 grm. meat; (2) after 500 

 grm. meat and 150 grm. fat; (3) after a meal of 500 grm. meat; (4) and 

 (6) both represent the excretion in a fasting animal. (From TIQEKSTEDT 

 after FEDBR.) 



We are therefore justified in regarding urea as to a large extent exogenous in 

 origin, and as derived directly from the nitrogenous moiety of the protein 

 molecule, which may not at any time have formed part of the living tissues 

 of the bodv. 



