. RESPIRATION 279 



and -water in the respired air (p. 277), slowly 

 turning the guinea-pig jar from side to side, so 

 that the animal shall be kept in gentle motion 

 during an hour. 



The excretion of carbon dioxide is increased by 

 muscular exercise. 



Individual Level of Proteid Metabolism. Each 

 group of eight students will select two subjects 

 for experiment. They should be thin men in 

 good health. Let each subject collect the twenty- 

 four hours' urine in a thoroughly clean bottle of 

 about 2000 c.c. capacity. Measure the quan- 

 tity. Determine in a measured portion of the 

 total mixed urine the quantity of urea (hyppbro- 

 bromite method). Calculate the nitrogen in the 

 urea. Add 2.5 grams for the nitrogen excreted 

 in the faeces, sweat, and as uric acid in the 

 urine. 



Kepeat these determinations for three days, the 

 subject maintaining his usual diet and mode of 

 life. 



The excretion of nitrogen will probably be 

 found to be fairly uniform in each individual 

 though the different nutritive habits of different 

 individuals may cause them to be on different 

 proteid planes, characterized by high, medium, or 

 low nitrogen excretion. 



Nitrogenous Equilibrium. When the daily. 



