CARBOHYDRATE METABOLISM AND GROWTH IX EDIBLE CANNA 7 
and evaporated over a steam bath to about 15 cubic centimeters. 
Water was then added and the solution transferred to a flask graduated 
to 100 cubic centimeters and clarified with neutral lead-acetate solution. 
After this, the regular method was adhered to, the reducing sugars 
being determined by the method of Munson and Walker (1, p. 78). 4 
Inversion was effected by allowing the solution to stand with hydro- 
chloric acid for 12 hours at room temperature. In all cases the 
hexoses were calculated as invert sugar. 
PRESERVATION* OF SAP SAMPLES FOR ANALYSIS 
Obviously, it was necessary to prevent changes in the sugars of 
sap samples collected in the field. In the first trial 25 cubic centi- 
meters each of sap from rootstock and stem was treated with formalin 
(40 per cent formaldehyde), stored for three days, and analyzed. 
Table 1 shows the changes taking place in the sugars of the sap on 
standing with formalin as a preservative. 
Table 1. — Effect of formalin (40 per cent formaldehyde) on the sugars of samples of 
sap from the canna plant 
Test 
No. 
Sucrose 
Hexoses 
Source of sap and treatment with 
formalin 
Fresh 
sample 
Stored 3 Fresh 
days sample 
. /Rootstock (4 drops) 0.95 
1 \Rootstock (12 drops) .95 ' 
2 Do 1.01 I 
, /Stem (4 drops) .42 
"* (Stem (12 drops) j .42 
4 Do '. .27 
0.86 
.83 
.93 
.13 
.19 
.08 
0.09 
.09 
.15 
.39 
.39 
1.26 
Stored 
days 
Per cent Per cent Per cent Per cent 
0.21 
.37 
.37 
.72 
.75 
1.56 
Total sugars 
Fresh Stored 3 
sample days 
Per cent 
1.04 
1.04 
1.16 
.81 i 
.81 J 
1.53 
Per cent 
1.07 
1.20 
1.30 
.85 
.94 
1.64 
Formalin did not prevent inversion of sucrose, although there was 
no loss in total sugars when it was used; in fact, the total sugars 
slightly increased in the juices treated with formalin, the percentage 
of sugars increasing with the increased quantities of formalin used. 
Ethyl alcohol was next tried as a preservative, 25 cubic centimeters 
of sap being pipetted into 50 cubic centimeters of 95 per cent alcohol 
that had been freshly prepared by distillation with sodium hydroxide. 
Two procedures were followed. In one the samples were filtered at 
once, and the clear alcoholic filtrate stored; in the other the unfil- 
tered samples were stored. Table 2 gives the results of the tests. 
Table 2. — Effect of ethyl alcohol on the sugars of samples of sap from the canna 
plant 
Sam- 
ple 
No. 
Source of sap and treatment 
1 Stem, fresh- 
2 Stem, not treated, stored 3 days 
3 Stem, stored in alcohol 3 days, then filtered 
4 Stem, alcoholic filtrate stored 3 days 
1 Rootstock, fresh - 
2 Rootstock, not treated, stored 3 days 
3 Rootstock, stored in alcohol 3 days, then filtered. 
4 Rootstock, alcoholic filtrate stored 3 days 
Sucrose 
Per cent 
0.34 
.02 
.28 
.30 
me 
1. 1.-. 
1.14 
Hexoses 
Per cent 
1.45 
.71 
1.46 
1. 4.", 
.23 
.07 
.25 
.25 
4 Reference is made by number in italics to Literature cited, p. :i4. 
Total 
sugars 
Per cent 
1.79 
.73 
1.74 
1.75 
1.39 
.07 
1.40 
