902 METABOLISM. 



of calcium phosphate by the skeleton. It is impossible to give 

 positive figures for the need of phosphates or phosphoric acid, whose 

 value is recognized not only in the construction of the bones, but also 

 in the functions of the muscles, the nervous system, the glands, the 

 organs of generation, etc. The extent of this need is most difficult to 

 determine, as the body shows a strong tendency, when increased amounts 

 of phosphorus are introduced, to retain more than is necessary. The 

 need of phosphates, which, according to EnRSTROM, 1 corresponds in adults 

 to a minimum of 1 to 2 grams phosphorus, is relatively smaller in adults 

 than in young, developing animals, and in these latter the question of 

 the result of an insufficient supply of earthy phosphates and alkaline 

 earths upon the bone tissue is of special interest. For details we refer 

 to Chapter IX and to the cited work of ALBU-NEUBERG. 



Another important question is, How far do the phosphates take part 

 in the construction of the phosphorized constituents of the body or to 

 what extent are they necessary? The experiments of ROHMANN and his 

 pupils 2 with phosphorized (casein, vitellin) and non-phosphorized pro- 

 teins (edestin) and phosphates show that with the introduction of casein 

 and vitellin a deposition of nitrogen and phosphorus takes place, while 

 with non-phosphorized protein and phosphates this does not seem to 

 occur. The body apparently does not have the power of building up 

 the phosphorized cell constituents necessary for cell life from non-phos- 

 phorized proteins and phosphates. On the contrary, according to the 

 observations of several investigators, the lecithins seem to possess this 

 power. As known from the investigations of MEISCHER, the develop- 

 ment of the generative organs of the salmon, which are very rich in nuclein 

 substances and phosphatides, from the muscles which are relatively poor 

 in organic-combined phosphorus, seem to indicate a synthesis of phos- 

 phorized organic substance from the phosphates. The investigations 

 of HART, McCoLLUM and FULLER, S who found that pigs with food 

 poor in phosphorus develop just as well with inorganic phosphates as 

 with organic phosphorus compounds, also indicate such a formation. 

 The recent investigations of MCCOLLUM 4 on rats show that these animals 

 can take up the entire need of phosphorus for the skeleton as well as for 

 the reformation of nucleins and phosphatides in the form of inorganic 



1 Skand. Arch, f . Physiol., 14. 



2 The literature on feeding experiments with phosphorized and non-phosphorized 

 food can be found in McCollum, Amer. Journ. of Physiol., 25. 



3 Hart, McCollum and Fuller, Amer. Journ., of Physiol., 23. See also Lipschiitz, 

 Pfliiger's Arch., 143. The literature on the phosphorus metabolism can also be 

 found in Albu and Neuberg, Physiologic und Pathologic des Mineralstoffwechsel, 

 Berlin, 1906. 



4 Amer. Journ. of Physiol., 25. 



