CARBOHYDRATE METABOLISM AND GROWTH IN EDIBLE CANNA 31 
(7). 9 Determinations were made in duplicate in the rootstock and 
stem samples. The results are given in Table 13. 
Table 13. — Osmotic pressure and freezing-point depression of sap from the canna 
plant 
Rootstocks 
Stems 
Leaves 
Stage of maturity 
Depression 
of the 
freezing 
point 
Osmotic 
pressure 
Depression 
of the 
freezing 
point 
Osmotic 
pressure 
Depression 
of the 
freezing 
point 
Osmotic 
pressure 
{ 
°C. 
0.789 
.797 
Atmosphere 
9.502 
9.599 
°C. 
Atmosphere 
°C. 
Atmosphere 
Average 
.793 
9.551 
{ 
.810 
.833 
9. 755 
10. 933 
0.763 
.753 
9.190 
9.069 
Average 
.822 
10. 344 
.758 
9.129 
Group3a 
{ 
.726 
.785 
8.745 
9.454 
.804 
.821 
9.683 
9.887 
Average 
.756 
9.099 
.813 
9.785 
0.683 
8.227 
{ 
.772 
.781 
9.298 
9.406 
.614 
.694 
7. 397 
8.360 
Average 
.777 
9. 352 
.654 
7.879 
.592 
7 132 
The results given in Table 13 are not sufficient to warrant definite 
conclusions. However, the close agreement of the results with the 
variations in the sugar content of similar samples is worthy of note. 
The osmotic pressure reached its maximum in the rootstocks of 
Group 2 and diminished through Groups 3a and 3b, which also was 
true of the sucrose. Since usually the hexoses in the rootstocks were 
negligible, the total sugars showed the same variation. The osmotic 
pressure in the stem reached its maximum in Group 3a, whereas the 
sugars were greatest in Group 2. However, the rise and subsequent 
decrease of the hexoses and total sugars in progressing from Group 1 
to Group 3b were apparent in the osmotic pressure. Moreover, the 
differences in the depression of the freezing points of the rootstocks, 
expressed in terms of sucrose, were practically the same as the differ- 
ences in the total sugars of the rootstocks given in Table 7. The 
same was true of the hexoses of the stems. The difference in the 
average depression of the freezing point of the rootstock of Groups 
2 and 3b, for example, was 0.45° C, which is equivalent to 0.83 per 
cent sucrose, whereas the difference in the total sugars of Groups 2 
and 3b (samples Nos. 3 and 6, Table 7), was 1.01 per cent. Although 
exact figures have no significance in this connection, since the freez- 
ing point and the sugar determinations were made on different samples 
representing the same group of rootstocks, the comparisons are worthy 
•The determinations were made at the station in 1924 by Charles C. Crane, under the direction of 
J. A. Harris, department of botany. University of Minnesota. Doctors Harris and R. A. Oortner, also 
of the University of Minnesota, used the chemical laboratory facilities of the station in obtaining cryo- 
scopic and conductivity data on Hawaiian plants, in exchange for which courtesy they collected the canna 
samples and turned over to the station the data accumulated. 
