Aug. i, 1921 Changes Caused in Sweet Potatoes by Rhizoptis tritici 629 
EXPERIMENTAL DATA 
respiration 
The results of all the respiration experiments expressed in grams of 
C0 2 given off for each 24-hour period as well as the total for the duration 
of the experiment are given in Table I. 
Table I. — C 0 2 output from a decaying and a sound half of the same sweet potato at the end 
of each 24-hour period a 
Experiment 
No. 
605 
609 
631 
6 37 
Sample. 
First day. 
Second 
day. 
/Control . 
0.6210 
1 .Ain a 
0.4807 
4-I653 
•9 I 47 
8 Cn 7 a 
(Rotted. 
/Control.. 
x • TO / 
. OIAA 
(Rotted. 
• y -1 -J- * f 
1-9583 
•7153 
I.O726 
. 2010 
/Control. 
.4986 
5-0479 
•4173 
3-9748 
(Rotted.. 
/Control. 
(Rotted . 
• oy 
.9813 
Third day. 
Fourth 
day. 
Total. 
O.4652 
1.5669 
4.2861 
9.8888 
•9145 
2.7436 
8 -7363 
19.2880 
.4807 
I.6946 
6.5600 
12.6805 
•35° 2 
0.4287 
1.5872 
4.1859 
3.3626 
12.5046 
a Expressed in grams. 
It will be noted that the C 0 2 output at the end of the first 24 hours 
was considerably greater in the decaying than in the control half. This 
difference was further increased during the next 2 days. In the first 
three experiments decay was completed in 3 days and in the last one in 4 
days. As shown by the last column a total of from 6.3 to 7.8 times as 
much C 0 2 was evolved by the decaying half as by the control. 
The figures presented in Table I should not be interpreted as repre¬ 
senting exactly what happened in each individual case. In other words, 
an allowance should be made for variations in respiration that would 
normally take place between two sound halves of the same potato of 
equal weight. It was shown by Hasselbring and Hawkins (7) that 
wounding accelerates the C 0 2 output of sweet potatoes. Preliminary 
to the experiments, the results of which are recorded in Table I, the daily 
evolution of C 0 2 from the corresponding halves of several sound sweet 
potatoes was determined for the purpose of ascertaining the probable 
error. The two halves were held under similar conditions, and the C0 2 
was collected for 24-hour periods. The greatest variation w^as about 
11 per cent, but in most cases it was very much less. If a correction of 
this variation were made in each individual experiment it would not be 
sufficient to alter materially the ratio of the C 0 2 output between the 
rotted and control halves. 
CARBOHYDRATE CHANGES 
In living potatoes.— As soon as decay was complete the halves 
were removed from the respiration chambers, pulped, and prepared for 
the determination of starch, cane sugar, reducing sugar, and percentage 
of moisture. The results of these analyses are shown in Table II. 
