1911.] Substances upon the Autofer mentation of Yeast. 451 



this question, in an earlier work* the conclusion was reached that most salts 

 are probably not capable of penetrating beyond the outer layers of the 

 cytoplasm. This would render any specific action upon the enzyme very 

 doubtful. Moreover, it is improbable that so many different salts should 

 exert a similar effect. Further, such action, if exerted in the cell, should also 

 be exhibited in the contents after removal from the cell. The following table 

 shows the result of addition of salt to yeast-juice both in presence and absence 

 of added sugar : — 



Table III. — Effect of Sodium Chloride upon Fermentation by Yeast-juice. 





Cubic centimetres of carbon dioxide evolved by 25 c.c. of 

 yeast-juice in 18 hours. 



Sugar free 



Control. 

 35 -3 

 55 -9 



+ '14 grm. 

 NaCl. 

 28 -0 

 42-2 



+ -36 grm. 

 NaCl. 

 18 -2 



29-8 



+ -72 grm. 

 NaCl. 



8-2 

 14 -5 



+ 1 -45 grm. 

 NaCl* 



2- 2 



3- 1 



+ 1 grm. glucose... 



* Molar concentration. 



These numbers prove that the autofermentation is diminished in practically 

 the same proportion as the sugar fermentation, and they afford no evidence of 



acceleration of the action of the glycogenase. 

 Very similar results were obtained with zymin. 



Table IV. — Effect of Sodium Chloride upon Fermentation by Zymin. 





Cubic centimetres of carbon dioxide evolved by 5 grm. 

 zymin + 20 c.c. solution in 5 hours. 



+ 1 grm. glucose 



"Water. 



77 -2 

 173 -2 



M/10 NaCl. 

 64 -0 

 162 "4 



M/4 NaCl. 

 51-7 

 136 -2 



M/2 NaCl. 

 32 4 

 83 -5 



It follows from these experiments that the direct action of salt upon the 

 enzymes of yeast is that of an inhibitant, and that the acceleration of the 

 autofermentation of yeast by salt cannot be due to a specific effect of the latter. 

 This, however, does not exclude the possibility that certain substances which 

 accelerate the action of yeast-juice and zymin may also exert a specific effect 

 upon the autofermentation. 



(2) Plasmolysis of the Cell. — It has been demonstrated by Paine that with 

 molar concentration of sodium chloride strong plasmolysis occurs, while 

 deeimolar solution produces no such result. The effect of these concentrations 

 upon the autofermentation of yeast is shown in the following table : — 

 * Paine, loc. cit. 



VOL. LXXXIV. — B. 2 L 



