46 METABOLISM OF ORGANIC AND INORGANIC PHOSPHORUS. 



by this same method, which precludes the possibility of any phos- 

 phorus in this form being normally present in the urine of rabbits. 

 In Table VI, where the total phosphorus is determined by the 

 Neumann method and the inorganic phosphorus by tit ration with 

 uranium acetate, the difference is called organic phosphorus. That 

 the uranium acetate method is not absolutely correct is indicated 

 by the figures which in several cases show more phosphorus by this 

 method than by the Neumann method. *In the case of rabbit No. 4 

 and in one instance in the case of rabbit No. 3 the differences are too 

 large to be explained on the basis of experimental error. It is 

 certain from these results that the ingestion of organic phosphorus 

 does not cause an increased elimination of organic phosphorus in the 

 urine; but the fact that in the case of the rabbits fed inorganic phos- 

 phorus there should be an apparent elimination of organic phosphorus 

 in the urine in some cases must be explained on the basis of the 

 endogenous origin of the organic phosphorus of the urine which 

 appears to take place only in abnormal cases. 



CALCIUM AND MAGNESIUM BALANCES. 



During the principal metabolism experiments, lasting four weeks, 

 the calcium and magnesium balances were determined in addition 

 to those of nitrogen and phosphoric acid. The amount of calcium 

 ingested per seven-day period varied from 0.44 to 0.58 gram per 

 1,000 grams body weight, while that of magnesium varied from 0.15 

 to 0.21 gram, rabbit No. 1 receiving more than rabbits Nos. 3 and 4, 

 while rabbit No. 2, which died at the end of the first two \veeks, 

 received about the same amount as rabbits No. 3 and No. 4. Goitein 

 states that unless a rabbit receives 0.16 gram of calcium per kilo body 

 weight, a loss of calcium will occur. The figures show that the rabbits 

 under this observation received far more than that minimum amount 

 and, therefore, were in no danger of calcium starvation. 



The figures in Table VII show that the calcium excreted in the 

 urine was 9 per cent for No. 1, 10.8 per cent for No. 2, 4.2 per cent 

 for No. 3, and 4.9 per cent for No. 4. In the case of the rabbits fed 

 organic phosphorus, the average amount of calcium absorbed from 

 the intestinal tract or metabolized was higher than in the case of 

 those fed inorganic phosphorus. These figures agree with the theory 

 that the calcium and phosphorus in the inorganic form unite to form 

 the insoluble calcium phosphate, which is eliminated by the bowels 

 in unchanged form. 



Arch, gesam. Physiol., 1906, 115 : 118. 



