370- 



ARON AND HOCSON. 



47 per cent (experiment number 4) of the nitrogen taken. The nitrogen 

 contained in the outer layers of the rice, whether taken with the grain 

 (experiment number 3), or in the forai o^ the material milled off from 

 the grain and added to the food (experiment number 11) is absorbed only 

 to the extent of about 25 per cent. Therefore, the fact that the nitro- 

 gen content of red rice is somewhat higher than that of the white variety 

 is of no physiological importance. 



Riibner found about 75 per cent of the nitrogen in rice to be absorbed, Mori 

 as much as 78.3 per cent. On the other hftnd, Thomas and Yukawa give values 

 agreeing more closely with ours, namely, 67.4 per cent and 66.1 per cent, 

 respectively. 



The nitrogen in the faeces does not consist solely of that not absorbed from 

 the foodstuffs, but it is partly present as nitrogen from the secretions of the 

 intestinal tract. Therefore, the quantity of unabsorbed nitrogen, e.xpressed in 

 percentage of the nitrogen taken, must be proportionally higher the lower the 

 nitrogen intake is. This explains the fact that not only in our work, but also 

 in that of Thomas ° and Yukawa,'" a lower percentage of the nitrogen taken 

 was found to be absorbed, even with a lower nitrogen intake, than was the case in 

 the experiments of Riibner," Kellner, and Mori. The percentage of absorption 

 of nitrogen when the diet consists of bread and rice is practically the same as 

 in the case of white rice alone. This is made plain by comparing experiments 

 numbered 5 to 7 with numbers 1 and 2. 



The experiments with mixed diet are interesting, as is shown by Table VI. 



Table VI. — Experitnents with mimed diet. 



In the food. 



1 Ex peri- I 



i ment Veee- 



i number. I Animal tnvflp 



! :""rogen.|„j^o^„ I nitrogen. 



Total 



Quantity 

 of nitro- 

 gen in 

 faeces. 



Absorp- 

 tion of 

 nitrogen 

















Grams. 



Grams. 



Grams. 



Grams. 



Per cent: 







0.31 



9.26 



9.57 



3.39 



64.6 



6 



0.25 



9.16 



9.41 



3.23 



65.7 



7 



1.95 



9.11 



11.06 



3.38 



69.4 



10 



2.52 



8.47 



10.99 



2.64 



76.0 



13 



4.87 



5.90 



10.27 



2.27 



77.9 



12 



4.37 



5.90 



10.27 



2.03 



81.0 



8 



4.26 



-5.66 



9.92 



2.15 



78.3 



14 



2.62 



5.28 



7.90 



1.98 



74.9 



9 



2.84 



4.76 



-.60 



1.64 



78.4 



Nitrogen 

 of fseces 

 in per 

 cent of 

 animal 

 nitrogen 

 in food. 



Per cent. 

 36.5 

 35.2 

 37.1 

 31.2 

 38.5 

 36.0 

 37.9 

 37.5 

 34.4 



The smaller the proportion of vegetable nitrogen in the food the greater 

 relatively, is the absorption of nitrogen. The nitrogen content of the 

 fseces is practically directly proportional to the quantity of vegetable 

 nitrogen in the food, and is influenced but little by the amount in the 



" Log. cit. 



"•Arch. Verd. Kreht. (1910) 15, 4-5. 



'■■ Zl.'^clu: niol. (1889) 25, 102-22. 



