32 METABOLISM OF ORGANIC AND INORGANIC PHOSPIHUH 



-odium was given to all four rabbits, and the total amount of phos- 

 phoric acid fed was practically equalized. 



Gluten was selected as a food high in nitrogen but containing little 

 phosphoric acid. The usual method of washing out the starch from 

 coarse flour was employed. The moist gluten was spread out on 

 sheets of tin and dried on the steam bath. After several days of 

 this treatment the samples were sufficiently dried for grinding, and 

 contained from 12 to 13 per cent of nitrogen. 



The organic phosphorus was supplied in the form of phytin, a cal- 

 cium-magnesiiim-potassium compound of anhydro-oxy-methylene- 

 di-phosphoric acid which was first isolated by Pasternak." This 

 was prepared by extracting wheat bran with 0.2 per cent hydro- 

 chloric acid, allowing the starch to settle, decanting off the clear 

 liquid, and to this adding a large volume of 95 per cent alcohol. A 

 heavy flocculent precipitate formed. This was allowed to settle and 

 after the clear liquid Lad been decanted off, the remainder was fil- 

 tered. The precipitate was then dried at room temperature by 

 blowing air over it by means of an electric fan. In this air-dried 

 condition the phytin contained from 22 to 30 per cent of phosphorus 

 (P 2 O 5 ) in organic form. The uranium acetate titration method 

 showed that no inorganic phosphorus was present. 



The nature of phytin has been investigated by Patten and Hart, 6 

 who gave to it the following composition: Calcium, 1.13; magne- 

 sium, 5.80; and phosphorus, 16.3 per cent. 



Phytin on heating with mineral acids is decomposed into inosite 

 and phosphoric acid. The investigators just quoted claim there is 

 no decomposition of phytin by enzyms and the same conclusion was 

 reached by Mendel and Underbill, who also studied this ques- 

 tion. It is claimed that the proteolytic enzyms of the alimentary 

 tract do not alter phytin, but that the alteration is brought about by 

 the intestinal epithelium. The free acid phytin corresponds to the 

 formula C 2 H 8 P,O 9 . The alkali salts are freely soluble in water and 

 the calcium and copper salts are slightly soluble in water, while the 

 barium and strontium salts are but sparingly soluble in water. Phy- 

 tin has thus far been found in peas, beans, pumpkin seeds, and red 

 and yellow lupines. The carbohydrates of the food were supplied 

 by feeding a mixture consisting of equal portions of cane sugar and 

 cornstarch. The fat used w^as olive oil. 



The food was prepared in the following manner: The carrots were 

 first chopped into small pieces and a portion was mixed with part of 

 the gluten-starch-sugar mixture. To this was added the phytin and 

 5 cc of the phosphoric-acid-free salt solution in the case of the rabbits 



Rev. gen. bot., 1900, 12 : 5. 

 &Amer. Chem. J., 1904, 31 : 564. 

 cAmer.-J. Physiol., 1906, 17 : 7.",. 



