30 METABOLISM OF ORGANIC' AND INORGANIC PHOSPHORUS. 



somewhat more than 1 gram, and of this amount two-thirds is mag- 

 nesium and one-third calcium phosphate. In acid urines the simple 

 as well as the double acid earthy phosphates are found, and the 

 solubility of the former (among which the calcium salt, CaHPO 4 , is 

 especially insoluble) is particularly augmented by the presence of 

 double acid alkali phosphates and sodium chlorid in the urine (Ott). 

 The quantity of alkaline earths in the uryio depends upon the com- 

 position of the food. 



MAGNESIUM COMPOUNDS. 



The relative ratio of magnesiui i to calcium as eliminated by the 

 body is 1 : 8 or 1:9, and consists largely of magnesium phosphate, 

 Mg 3 (PO 4 ) 2 . The amount of magnesium required by the body per 

 duv is 0.6 gram. As in the case of iron, though magnesium is neces- 

 sary to health, but little magnesium is found in the child's food, 

 namely, milk. The need of magnesium in the system has been 

 studied by Bunge. b The magnesium balances have been studied by 

 Blauberg, c Cronheim and Miiller/ Bertram/ and Ren vail/ but are 

 not considered as important as the calcium. Moreover, little study 

 has been given to the elimination of magnesium under pathological 

 conditions. 



The elimination of phosphoric acid, calcium, and magnesium de- 

 pends principally on the character of the food and the relative pro- 

 portion of animal and vegetable food digested. 



A FEEDING EXPERIMENT WITH RABBITS. 

 PLAN OF THE EXPERIMENT. 



In these experiments four female rabbits were used, the diet con- 

 taining as little phosphorus as possible. To two of the rabbits organic 

 phosphorus in the form of crude phytin was fed, and to the other 

 two an equivalent amount of phosphorus in the form of sodium 

 phosphates was given. 



It was intended to keep these four rabbits on their respective diets 

 for three or four months, in order that they might become accus- 

 tomed to the added phosphorus and, further, that it might be com- 

 pletely anabolized, and then to mate them and feed the young rabbits 

 on the same kind of food and on phosphorus in the same respective 

 combinations as that fed to the mother rabbits. When the young 



Zts. physiol. Chem., 1886, 10 : 1. 



bZta. Biol., 1874, 40 : 111, 295. 



clbid., 1900, 40:1. 



dZts. diat. physik. Therapie, 1902-3, 6 : 25, 92. 



Abs., Chem. Centrbl., 1879, 10 : 526. 



/Skand. Arch. Physiol., 1904, 16 : 94. 



