Mason — Inhibition of Invertase in the Sap of Galanthus nivalis. 91 



be masked by the greater velocity of hydrolysis in the initial stages of 

 storage ; but, with the introduction of factors limiting hydrolysis, a diminution 

 in the depression of the freezing-point would be brought about. 



In Table VII are shown the results obtained with a sample of sap pressed 

 from leaves which had been exposed to toluene vapour for four hours. To 

 25 c.c. of this sap approximately 2 grams of invert sugar and sucrose 

 respectively were dissolved. 



These leaves were collected at 9.30 a.m. on April 22nd. 



Table VII. 



This experiment does not call for comment, as it confirms the results of 

 the last experiment. 



There is no condensation of hexoses in the hexose-sap solution. 



Bonns (2), in his work on etherization and enzyme activity, found that 

 factors inhibiting the activity of invertase were introduced by exposure to 

 ether vapour. 



Possibly the slight decrease in the depression of freezing-point brought to 

 light in these experiments may be attributed to the oxidation of hexoses. 



In Table VIII are given the results of an experiment designed to determine 

 if the sap pressed from material treated with toluene exerted an inhibiting 

 influence on the invertase of yeast. To 50 c.c. of the sap 2 grams of sucrose 

 were added. 



The invertase solution was diluted with an equal volume of water, and 

 evidently had much the same depression as the sucrose-sap solution, since 

 its addition has produced only a very slight reduction in the depression. For 

 comparison some of the sap was boiled before the addition of the invertase. 

 In the last column is shown the increase in depression after storage at 29"" for 

 twenty-four hours. 



