304 



Mr. S. G. Paine. 



[July 12, 



In the estimations, the organic matter was destroyed by Neumann's method 

 and the phosphoric acid was precipitated with magnesium citrate mixture. 



With the weaker concentration, which was found to be isotonic with yeast, 

 no exchange of phosphoric acid took place, but from a solution containing 

 4 per cent, of sodium phosphate, approximately 0*3 molar, entrance of 

 phosphoric acid into the cells was well marked. 



Sodium Hexosephosphate. 



For the purpose of this research hexosephosphate was of all substances 

 of greatest interest, since Harden and Young (13) have found that hexose- 

 phosphoric acid is continually being built up and broken down again in the 

 fermentation of sugar by yeast-juice. When they added this substance to 

 living yeast, however, no evidence of its fermentation could be obtained. It 

 was of special importance, therefore, to determine whether any of the 

 substance had been able to diffuse into the yeast-cells. 



The solution of hexosephosphorie acid was prepared by the method 

 described by Young (14) and was neutralised to litmus with caustic soda. 

 Four concentrations of the salt have been employed and the results are 

 given in the following table. In each case the time of standing was 20 hours 

 at a temperature between — 2 and 0°. 



Table XI. — Diffusion of Sodium Hexosephosphate. 



No. 



Conditions. 







Liquid. 





Initial. 



Final. 



Initial. 



Final. 



169 



Concentration, '035 molar = "14 

 normal. Standing 20 hrs. in cold 



Total 



Po0 5 



100 -oo 

 1 "42 



89 -80 

 1 -36 



100 -oo 



O-50 



110 -20 

 0-51 



174 



Concentration, ■ 06 molar = -24 

 normal 



Total 

 P 2 5 



100 -oo 

 1 42 



102 -50 

 1 -55 



100 -oo 



0-84 



97 -50 

 0-80 



172 



Concentration, '126 molar = 0'504 



Total 



P.A ... ■ 



100 -oo 

 1 -26 



92-90 

 1 -52 



100 -oo 

 1-80 



107 -10 

 1 -56 



177 



Concentration, - 23 molar = '93 



Po0 5 



100 -oo 

 1-66 



92 -66 

 1 -99 



100-00 

 3-33 



107 -34 

 2-98 



The results are strikingly similar to those obtained with sodium phosphate. 

 Where the concentration was small, as, for instance, in Experiment 169, no 

 definite entrance of phosphorus took place; with higher concentrations, 

 however, the increase of P2O5 in the yeast became well marked. Experi- 

 ment 177 showed that 033 grm. of P2O5, equal to 2 - 5 c.c. of molar solution 



