240 WILLIAM J. ROBBINS 
Table II 
Time in 
Min. 
Undigested 
Starch (Mg. 
per 20 Cc.) 
Starch Digested 
(Mg. per 20 Cc.) 
Starch Digested 
per Minute 
Cuprous Oxide 
(Mg. per 20 Cc.) 
Starch Digested 
Calculated from 
Maltose Deter- 
per 20 Cc.) 
Starch Di- 
gested per 
Mmute 
0 
344-1 
12.4 
i6 
334-5 
9-6 
.60 
23-5 
6.4 
-4 
29 
325-4 
18.7 
.64 
32.7 
13-3 
.46 
44 
314-9 
29.2 
.66 
44-5 
22.2 
•50 
60 
305-5 
38.6 
.64 
54-8 
30.0 
•50 
80 
304-7 
39-4 
•49 
74-5' 
44.76 
•51 
100 
276.7 
. 67.4 
.67 
82.3 
50.6 
•51 
123 
264.9 
79.2 
.64 
98.0 
62.4 
•51 
151 
242.5 
101.6 
.67 
1 16.9 
76.6 
•51 
185 
229.6 
114-5 
.62 
138.8 
93-1 
-50 
245 
192.5 
151. 6 
.62 
178.3 
122.7 
•50 
323 
164.2 
179.9 
.56 
224.0 
156.9 
.48 
420 
122. 1 
222.0 
-53 
275.2 
195-3 
.46 
549 
85.6 
258.5 
•47 
321.7 
230.1 
.42 
702 
69.6 
274-5 
•39 
339-8 
243.6 
-35 
is soluble in 73 percent alcohol, and the amount of this material in- 
creases with the time of digestion. 
Calculating the digestion per unit of time, it would seem that, 
measured by either method, the amount of starch digested is pro- 
portional to the time for the first 245 minutes or until about 44 per- 
cent of the starch is in such form as is soluble in 73 percent alcohol. 
From that point on, the starch digested per unit of time steadily 
falls off. 
The close correspondence of the two methods can be noted from 
the curves in figures 2 and 3, in which the time in minutes is given on 
the abscissae and the amount of digestion in milligrams on the ordinates. 
In figure 2 the line parallel to the base at 344 mg. represents the 
starch content of the original solution per 20 cc. as determined by 
alcoholic precipitation. By acid hydrolysis and sugar determination 
the starch content of the original solution was found to be 367.6 mg. 
per 20 cc. In figure 2 the results are plotted for the entire 702 minutes, 
in figure 3 for the first 151 minutes only. The latter figure shows 
clearly that, under the conditions of the experiment, in the earlier 
stages of diastatic action the amount of starch digested, measured by 
either method, is proportional to the time. 
It seemed probable that the difference between the digestion, as 
determined by the maltose produced and by the material precipitated 
^ Time for this determination was 87.5 min. 
