212 INFLUENCE OF FOOD PRESEEVATIVES ON HEALTH. 



TABLE XLIV Microscopical examinations of the urine for Series V Continued. 



METABOLIC PROCESSES. 



NITROGEN. 



BALANCE. 



As has already been intimated, the nitrogen balance represents the 

 difference between the total quantity of nitrogen in the foods and the 

 quantity secured in the feces and urine. In a perfectly normal state, 

 where the body is neither gaining nor losing in weight, this balance is 

 necessarily positive, because all the nitrogen contained in the food is 

 not found in the feces and urine. In abnormal states the balance may 

 become a negative number when more nitrogen is excreted by far 

 than should be, or it may become a greater positive number when less 

 nitrogen is excreted than should be. The tables illustrative of the 

 nitrogen balance are made out in full, containing the daily balances. 

 (See Tables XLV-LV, pp. 260-306.) The great variations in the daily 

 balance are largely due to the fact that the quantities of urine and feces 

 vary largely from day to day, while the quantity of nitrogen entering 

 into the food remains practically constant. Thus there may be very 

 great variations in the daily balance, while the balance for the period 

 is always approximately correct, especially if the period extends over 

 a considerable number of days. 



The largest deficiencies of nitrogen in the excreta are naturally 

 found in those cases where the percentage of excretion is low, and vice 

 versa. In the individual cases of Series I we find that the nitrogen 

 balance is a negative number in every period with No. 6, except dur- 

 ing the second preservative subperiod and the after period, where the 



