PHOSPHORUS FROM CASEINOGEN. 459 



A similar result had been arrived at by Biffi (3) , who, on boiling a 

 trypsin digestion of caseinogen with barium carbonate, ncrti^od <a$iincrease 

 of .inorganic phosphoric acid from 27 per cent, to 56 per cent. He also 

 obtained inorganic phosphoric acid on boiling his trypsm idigefetiori ^i^h 

 dilute caustic soda after previously removing the inorganic phosphoric 

 acid already present, but he made no estimation of its amount. 



There is, therefore, a very marked difference in the action of 1 per 

 cent, caustic soda on caseinogen directly and on caseinogen previously 

 digested by trypsin. In the former case, the total phosphorus is split off 

 as inorganic phosphoric acid, in the latter only 50 per cent, of the total 

 phosphorus is separated in this form. We are not yet able to explain 

 this difference, but it seems that the manner of the combination of the 

 phosphorus in caseinogen undergoes some change when it is acted upon 

 by trypsin ; if combined in the same way in the products produced by 

 trypsin as in the caseinogen itself it would be split off by 1 per cent, 

 caustic soda in 24 hours as inorganic phosphoric acid. The isolation of 

 this body containing phosphorus which is produced by the action of 

 trypsin and is resistant to 1 per cent, alkali is at present under 

 investigation, but we may state that it is completely precipitated by 

 ferric alum in the same way as paranucleic acid obtained by the action 

 of pepsin on caseinogen (Salkowski (16) ). 



(3) The soluble P 2 5 obtained by the action of pepsin. The clear 

 solutions filtered from the paranuclein of Experiments (4) and (5) were 

 employed and the following results were obtained : 



50 c.c. precipitated by magnesium citrate gave 1'77 mgm. 

 50 c.c. + 10 c.c. KH 2 P0 4 solution precipitated by magnesium citrate 

 gave 22-44 mgm. 



i.e. 50 c.c. gave 2-44 mgm. 



50 c.c. precipitated by magnesium citrate gave % 63 mgm. 



50 c.c. + 10 c.c. KH 2 P0 4 solution precipitated by magnesium citrate 



gave 21 '3 mgm. 



i.e. 50 c.c. gave 0'9G mgm. 



mean = 2-10 mgm. 



PoO, 



mean =0-96 mgrn. 



PoO, 



Thus, by the action of pepsin on caseinogen only a minute quantity 

 of inorganic phosphoric acid is formed. Salkowski in his experiments 

 obtained no inorganic phosphoric acid. Hence the soluble P 2 5 obtained 

 by the action of pepsin on caseinogen is combined in an organic form. 



