CIRCULATIOX OF PHOSPHORUS IN THE I'llOG 385 



salt. The filtrate thus obtained was acidified and the 1 N. HgSO^ solution obtained 

 was boiled for 7 minutes in order to split oil' the pja-ophosphate group of the 

 adenosintriphosphate. In other experiments, the solution was kept at 100° for 

 100 minutes. By this procedvire, the hoxosemonophosphate was liydrol>sed. 

 Other fractions were secured by hydrolysing the filtrate for some houi-s. The 

 non-hydrolysed phosphorus compounds remained in the filtrate together with 

 large amounts of neutral salts. From this solution, after wet ashing of the organic 

 compounds present, the phosphorus was precipitated as molybdenum compound. 

 The ammoniuni phosphomolybdate was dissolved in ammonia, and phosphorus 

 was precipitated as ammonium magnesium phosphate. 



The muscle fraction which does not dissolve in trichloroacetic acid contains 

 the phosphatides and the residual P. To secure the phosphatides, Bloor's method 

 was used. All fractions were ultimately obtained as ammonium magnesium phos- 

 phate which was dissolv^ed in dilute hydrochloric acid. An aliquot part of the 

 solution was used for the colorimetric determination of the phosphorus, accortling 

 to FiSKE and Subbarow, another aliquot part was applied in the radioactive 

 measurements. The comparison of the radioactivity of the P fractions is much 

 facilitated if all samples have the same weight. In this case, no correction for the 

 absorption of the ^-rays in the sample has to be made. Fractions of equal weight 

 were obtained by adding to the solution of each fraction 80 mgm of secondary 

 sodium phosphate and by precipitating all P present as ammonium magnesium 

 phosphate. The precipitates obtained were dried at 106°. Corrections for the decay 

 of the activity of the ^-P can also be avoided if all samples are measured relatively 

 to the same active phosphorus preparation. As such preparation an aliquot of 

 the solution administered was used, the P content of the preparation being con- 

 verted into ammonium magnesium phosphate, as described above. 



DISTRIBUTION OF PHOSPHORUS IN THE FROG 



We determined the phosphorus content of the different parts of the 

 frog by wet ashing of the organs followed by a phosphorus determination 

 by the method of Fiske and Subbarow. The results of these determina- 

 tions are seen in Tables 1 a and 1 b. 



ABSORPTION OF PHOSPHATE 



In order to get data on the rate of absorption of the lal)elled phosphate 

 injected into the lymph sack, we determined the activity of plasma 

 samples of known weight both of frogs kept at 0° and frogs kept at 

 18° at different times after injecting the labelled phosphate. The figures 

 obtained (see Figs. 1 and 2) are not a direct measure of the amount 

 of 32p absorbed but indicate the difference between the amount absorbed 

 into the circulation and the amount which left the circulation for the 

 organs. (The amount taken up by the corpuscles in the course of a few 

 hours is very restricted; see p. 400.) 



2.^ lievesy 



