50 Dr. Parkes on the Elimination of Nitrogen. [June 20^ 



The elimination of nitrogen by the nrine followed precisely the same 

 course in each man ; and allowance being made for the difference in food, 

 this course was identical with that determined in the former experiments, 

 when the diet was non-nitrogenous. It is certain that neither during 

 rest nor exercise did nitrogen pass off by the skin or lungs. 



It will be convenient to consider the total nitrogen in the first 

 instance. 



During the first period of four days the total nitrogen excreted was 

 71-428 grammes by S. and 74*008 grammes by B. In the period of rest, 

 instead of falling the nitrogen increased in amount, so that in two days 

 38-274 and 38-943 grammes were excreted. This is not only more than 

 the half of the previous four days, but more than the amount of either 

 the first two or the last two days of the first period. The greatest 

 increase was in the first day of rest, but in the second day the amount 

 was still above the mean of the previous period. 



As afterwards shown, this was not owing to lessened elimination by 

 the bowels ; for both the weight of the stools and the nitrogen increased 

 in the period of rest. It seems impossible to avoid the conclusion that 

 the condition of rest with an equal entry of nitrogen was accompanied 

 by a daily increase of excretion by the urine of about 1 gramme more 

 nitrogen. 



It may, indeed, be said that this is within the limits of error or un- 

 avoidable variation, and may be accidental ; but if so, it seems most re- 

 markable that the result should run in the same way and be of nearly the 

 same amount in each case, and be confirmed by the independent obser- 

 vation of the urea. In the third period, when the men returned to their 

 ordinary occupation, the nitrogen fell in both on the first day to a lower 

 point than had ever before been noted, and then rose gradually, so that 

 in the four days the amount was almost the same with that of the first 

 period, 70-45 and 73-94 grammes being excreted. In the period of 

 exercise which is to be compared with that of the rest, the results were 

 identical with those of the former experiments when nitrogen was not 

 supplied. 



On the first day of exercise the nitrogen in each man fell below the 

 corresponding day of rest by 1-626 and 1-131 gramme. In the next 

 twelve hours, which were almost entirely occupied in exercise, the dimi- 

 nution was still greater, being 2*498 and 1-225 grammes, which would 

 be equivalent to 5 and 2| grammes for twenty-four hours. In the last 

 twelve hours, of rest after work, the elimination increased greatly, so 

 that 5*142 and 3-331 grammes more were excreted than in the corre- 

 sponding rest-period ; the general result being that on the whole two 

 days' period of exercise, as compared with the whole period of rest, there 

 was an increase of about 1 gramme in the exercise-period in each man, 

 owing entirely to the large excretion in the last twelve hours. 



