THE INCOME AND OUTGO OF NITROGEN. 

 J. M. Bartlett. 



In conducting digestion experiments in which the urine can 

 be collected, it is customary to make a comparison between the 

 amount of nitrogen taken into the body and that excreted during 

 the same period. This comparison of the income and outgo 

 constitutes what is known as the nitrogen balance. It is made 

 for the purpose of ascertaining if the loss of nitrogen in the urine 

 and feces is made good by the food. Too much is not claimed 

 for the results thus obtained, since it is known that a part, at 

 least, of the nitrogen taken in is delayed in its passage through 

 the body. This nitrogen lag makes it impossible to tell if the 

 nitrogen excreted during any period exactly corresponds with 

 the income at any preceding period. Nevertheless, if the experi- 

 ment be continued for a considerable length of time, an equilib- 

 rium must at length be established. If the body is not gaining 

 weight, the outgo should now exactly counterbalance the income. 

 On the other hand, an excess of income nitrogen indicates a gain, 

 and a deficiency a loss in body weight. In the experiments 

 described in the preceding pages the feces and urine were col- 

 lected only after a preliminary feeding period of seven days, 

 when it would seem that the equilibrium must have been estab- 

 lished. 



The whole amount excreted by the sheep for the five days was 

 weighed, thoroughly mixed, and a sample drawn for analysis. 

 Each day's excretion from the steers was weighed and an aliquot 

 portion taken for a composite sample. The samples were pre- 

 served with formaldehyde. The following tables give the data 

 obtained on the urines in these experiments. 



