Dec. 20,1915 
Respiration Experiments with Sweet Potatoes 
the end of Table I is given the gain or loss of reducing sugar, calculated 
from the analytical data, and the glucose equivalent of the total carbon 
dioxid generated during each experiment, as actually determined. The 
percentages of reducing sugar in the sweet potatoes at the end of each 
experiment, without correction for changes in water content, were as 
follows: First experiment, 1.24 per cent; second, 1.22 per cent; third, 
1.39 per cent; fourth, 0.91 per cent; fifth, 0.71 per cent; sixth, 0.67 
per cent; seventh, 0.69 per cent. The experiments themselves will be 
described individually. 
Table I .—Composition and carbon-dioxid output of sweet potatoes at different times of 
the year 
Item. 
Period. 
Exper¬ 
iment 
1, Oct. 
21 to 
Nov. 5. 
Exper¬ 
iment 
2, Nov. 
7 to 
Nov. 17. 
Exper¬ 
iment 
3, Dec. 
9 to 
Dec 19. 
Exper¬ 
iment 
4 , Jan. 
4 to 
Jan. 15. 
Exper¬ 
iment 
5, Mar. 
26 to 
Apr. s- 
Exper¬ 
iment 
6, Apr. 
16 to 
Apr. 26. 
Exper¬ 
iment 
7, June 
x to 
June 11. 
Total sugar (as glu- 
[At beginning of ex per- 
2.62 
S' 80 
8.99 
6.22 
7 -o 3 
7 - 4 i 
7 * 30 
eose), per cent, 
(At end of experiment.. 
5 - 38 
5.08 
8.42 
5-82 
7*45 
7.40 
7- 20 
Cane sugar, per cent.. 
[At beginning of exper- 
< iment. 
[At end of experiment.. 
1.60 
3-95 
3-41 
3 - 72 
6.58 
6.74 
4-63 
4.71 
> 82 
6.42 
6 .17 
6.41 
6.08 
6.21 
Reducing sugar, per 
[At beginning of exper- 
| iment. 
•94 
2. 21 
2.06 
i- 35 
.90 
.92 
•90 
cent. 
[At end of experiment,. 
1. 23 
I. 18 
i -35 
.87 
.70 
.67 
.68 
fist day. 
27. 7 
24.9 
36.5 
73-9 
82.1 
138. 2 
46.6 
47 -S 
2d day. 
56.0 
3d day. 
116.4 
101.8 
92.9 
90.4 
84.9 
83*3 
76. 7 
48.4 
46.4 
43-4 
46.2 
4th day... 
60.0 
Si-8 
48.4 
48. 2 
46.8 
47 -S 
5th day.. 
O+t 9 i 
3 M 
31-8 
41. 7 
Daily rate of carbon- 
dioxid output, 
mgm. per kgm. per 
hour. 
6th day. 
7th day. 
40.4 
39 - 1 
34-8 
32. 8 
46.1 
46.5 
8th day. 
34-3 
31-6 
29. 8 
28.8 
9th day. 
39-8 
38.9 
41.4 
40*8 
10th day. 
nth day. 
12th day. 
28. s 
24.9 
3 i .7 
29.9 
9 - 77 
13th day. 
14th day.. 
15th day. 
Increment in reduc- 
-31.69 
25 - 85 
- 5-14 
~ 2.50 
ing sugar calculated 
from the analytical 
data, gm. 
Loss of reducing sugar 
equivalent to the 
carbon dioxid 
evolved, gm. 
35 -18 
15.80 
7 * 33 
Experiment i. —In this experiment 3,576.5 gm. of sweet potatoes 
were used. These were dug on October 20. The experiment was 
begun on the following day and continued until November 5. During 
that period the cane-sugar content rose from 1.60 to 3.95 per cent and 
the invert-sugar content from 0.94 to 1.23 per cent. The respiration 
rose somewhat during the first half of the period and then fell to a 
nearly uniform rate of approximately 28 mgm. per kilogram per hour. 
The rise at first, which was observed in nearly all the other experi¬ 
ments also, may in part be attributed to the rise of the temperature of 
12572 °— 15 -- 2 
