1913] HAWKINS—MALT DIASTASE 277 
So far as the writer has been able to learn, such retardation with 
dilute concentrations of sodium and potassium chlorides has not 
been recorded heretofore. KuEBEL,?° working with saliva, showed 
a slight decrease in the acceleration of hydrolysis at low concentra- 
tions of these two salts, but found no retardation such as is shown 
in table I, m/128 being the most dilute solution he used. This 
writer found a maximum acceleration between m/32 and m/128 
for these two salts, and a retardation with high concentrations. 
He used a colorimetric method for determining the velocity of 
hydrolysis, comparing with tubes of colored liquids the various 
colors. produced by the addition of iodine after a given time period. 
It is possible that results thus obtained may not be comparable 
with those of the present investigation, as the time intervals of 
transition between the different colored dextrins and between the 
last colored product formed, and achroodextrin may not be in 
the same proportion when the enzyme is activated by a salt as 
when no salt is added. Of course it must also be remembered that 
KUEBEL’s enzymatic mixture was saliva, while that here studied 
was barley diastase. 
GRUTZNER,™ using the same method of estimating diastatic 
activity as did KursBet, but working with pancreatic amylase, 
found the optimum concentration of sodium chloride to be between 
m/8 and m/32. 
For dialyzed ptyalin Cote found a slight decrease in the accel- 
eration with m/3000 sodium chloride, though acceleration at this 
point was still considerable. He found the point of maximum accel- 
eration to lie between m/4 and m/300. Experiments have been 
carried out upon the effect of sodium chloride on diastatic action 
by other investigators, with varying results. 
Calcium and magnesium chlorides, used singly, affect hydrolysis 
somewhat differently from the two monovalent salts. A decided 
retardation is evident at high concentrations, molecular for the 
calcium salt and m/2 for that of magnesium. This is in marked 
, F., Uber die Einwirkung verschiedener chemischer Stoffe auf die 
ete yr Mundspeichels. Archiv fiir die gesammte Physiologie 76: 276-305. 
2* GRUTZNE 2 Uber die Einwirkung verschiedener chemischer Stoffe auf die 
Thatigkeit des tiectechen Pankreasfermentes. Archiv fiir die gesammte Physiologie 
91°195-207. 1902. 
