(Vou 8 
66 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
acid increased the action of ptyalin, whereas larger amounts 
produced inhibition. He also noticed a difference in the acceler- 
ating action of acids in the presence of salts, an observation which 
was earlier reported by Wood (’94). 
The effect of the OH-ion concentration in NaOH and Na,CO, 
solutions upon the saccharogenie power of three different amy- 
lases, Taka, saliva, and an extract of swine pancreas, was deter- 
mined by Quinan (’09). Although no data on the exact OH-ion 
concentration were presented, the results are worthy of notice 
in that they show differences in the activities of the amylases 
employed. Using 100 mgs. of Taka diastase in 100 cc. of a 1 
per cent starch solution and allowing the digestion to proceed 
18 hours at 36° C., he found the critical hydroxyl-ion concen- 
tration, viz., the concentration at which merely a trace of sugar 
was present, in the solution containing 2 cc. of N/10 NaOH or 
6 cc. of N/10 Na,CO, Under the same conditions 1 ce. of 
saliva acting for 15 hours was found to yield a trace of sugar in 
solutions containing 1 ec. of N/100 NaOH or 4 ec. of N/100 
of Na,CO,. Similarly, in 10 hours, 1 ec. of an extract of swine 
pancreas yielded merely a trace of sugar in solutions containing 
approximately 3 cc. N/10 NaOH and less than 10 ec. of N/10 
Na,CO, The differences in the effects of these alkalis upon 
the various diastase activities, he stated, were due to differences 
in dissociation and thus in the amounts of OH ions present. 
Although the investigations by Sörensen (09) and those later 
by Michaelis (14) and his associates were not upon amylase 
specifieally, some of the results deserve mention in this con- 
nection. Sörensen, studying the factors influencing the activity 
of catalase and pepsin, concluded that the activity varied ac- 
cording to the actual H-ion concentration and not to the titra- 
table acidity. He also found that there existed one optimum 
H-ion concentration for each enzyme, regardless of the acid 
used, and this optimum was dependent upon the time and the 
temperature at which the enzyme was allowed to act upon the 
substrate. Thus, after a few minutes in the case of invertase, 
inversion occurred most rapidly at Py 3.68 and as the time in- 
creased the optimum was shifted toward the neutral point until, 
in 32 minutes, the optimum was P, 4.8. He further noted the 
similarity of the H-ion curve to the temperature curve in enzy- 
matic activity. 
