231 



were prepared according to the receipts of Clark and Lubs. The 

 pure chemicals I needed, were kindly supplied to me by Dr. I. M. 

 Kolthoff, whlle prof. Dr. W. E. Ringer personally tested the 

 strength of the solutions by electrolysis. I wish to thank thèse two 

 gentlemen whose valuable help enabled me to carry out thls part 

 of my mvestigation without encountermg too many difficulties. 



The expenment itself was very simple. A certain quantity of 

 enzyme solution (10, 15 or 20 ce.) was mixed with an equal 

 volume of a 0.16 or 0.32% starch solution. To obtain various de- 

 grees of acidity, I always added the standard solutions themselves 

 in volumes, equal to those of the enzyme and starch solutions. As 

 they are buffer solutions at the same time, H was constant through- 

 out the experiment. The P^ of the mixture was determined 

 and also the time, taken for the hydrolysis at the various degrees 

 of acidity. For further particulars I refer the reader to the articles 

 of Sorensen and Michaëlis. 



The results are plotted in the usual way in fig. I. This same 



Fig. 1. Influence of the hydrogen ion concentration on the action of the diastase 

 of Aspergillus niqer. 



