Upon STARCH-CONVERTING POWER OF .TAKA DtastasE 6] 
By referring to Table II it will be seen that in my work the 
general effects seem much the same for these acids as for the min- 
eral acids. Malic and acetic acid, however, after giving the usual 
acceleration near #/1,000, gave a marked inhibition as the dilution 
was carried further. This same peculiarity is shown by sulphuric 
and citric acids to a very much less extent. Malt diastase shows 
the same phenomenon. For instance, with acetic acid the accel- 
eration occurs in the region of 7/12,500 dilution, while n/62,500 
distinctly retards conversion. 
For taka diastase, malic acid did not stop conversion at n/1O, 
and at 7/100 gave a marked acceleration and still greater at 7/1,000. 
Then at 2/10,000 the inhibition was very marked. Acetic acid 
also did not stop conversion at #/10 concentration, but gave no 
acceleration until a dilution of ~/2,500 was reached, and at dilu- 
tions of 2/12,500 and »/62,500 gave almost as marked inhibition 
as malic acid. 
The work of Gillott * on the inversion of maltose by tartaric, 
citric and oxalic acids suggested that the apparent increase in the 
amount of sugar in my experiments with the dilute solutions of - 
these acids might be due to the inversion of the maltose into 
dextrose. To determine this a 7/10 solution of each of the acids 
used was allowed to act on a one-per-cent. solution of C. P. mal- 
tose for twenty-four hours at a temperature of 43° C. The solu- 
tions were then all neutralized and the coefficients of their reducing 
power determined and compared with that of the untreated one- 
per-cent. solution of maltose. There seemed to be. very little, if 
any, difference between them. It would seem, therefore, that the 
action of the weak acid is a true acceleration, and that the return 
to the normal action of the ferment at greater dilutions of the acid 
is due merely to weakening of the stimulus. There remains the 
chance that the effect of the acids during the breaking up and 
hydrolysis of the starch into maltose may cause the starch to be 
changed in part to grape sugar instead of maltose, and thus cause 
the increased reduction of Fehling’s solution. 
Among the workers who have dealt with the effects of salts 
and other bodies upon diastases, Chittenden and Ely + noted the 
* Gillott, Bull. Assoc. Belg. Chim. 13: 80, 119. 
/ t Chittenden & Ely, Journal of Physiology, 3: 327. 
