24 BULLETIN 56, HAWAII EXPERIMENT STATION 
proper begins to ascend the stalk with the development of the first 
leaf, and cell growth at the apex of the rootstock probably then 
rapidly decreases. In sample No. 5, Group 3a, the hexoses decreased 
to the same level as in the mature rootstocks of Groups 1 and 2. The 
starch, on the other hand, increased rapidly, the increase continuing 
through the Group 2 stage. 8 
A consideration of hill 3 shows that the entire hill was actively 
growing, the first generation still being in the Group 3a stage. This 
explains the low concentration of sugars in the stem. The presence 
of such large quantities of sugars, particularly of the hexoses in the 
rootstock, is noteworthy. The very low starch content in the root- 
stocks and the occurrence of starch in the stems leads to the conclu- 
sion that the hill was still in the process of establishment and that 
the rootstock had not begun to function with sufficient rapidity to 
convert the sugars into starch as fast as they were formed. 
Hill 4, 12 months old, from Waimea, showed variations in sugar 
very similar to those of hills 1 and 2 from the station. The hexoses 
of the stems were appreciably higher than in samples from the sta- 
tion. In view of the important part the mature stem apparently 
plays in the process of starch storage, it is significant that the hill 
had three generations of stems all of which functioned at nearly a 
maximum rate, whereas hill 1, which was of practically the same age, 
had only one generation. 
The solids other than starch, representing the resultant of all the 
other variable constituents, can be interpreted only in a very general 
way. Except for the first generation rootstocks, which are essentially 
different in structure from the others in the hill, the proportions of 
the solids other than starch were relatively constant as compared 
with the corresponding percentages of starch. Sample No. 15, for 
example, had only 0.65 per cent of starch, but was less by only 1.81 
per cent in solids other than starch than sample No. 2, which con- 
tained 25.83 per cent of starch. This appears to indicate that starch 
formation is the principal change taking place in the rootstock 
approaching maturity. 
A comparison of the analyses with data previously published by 
the station (3, p. 7) shows similar variations, depending upon the 
stage of maturity and age of the hill. The nitrogen-free extract, as 
shown in the earlier literature, was appreciably higher than was the 
proportion of starch in these investigations, because, in the former 
instance, all other carbohydrates hydrolyzed by 1.25 per cent sul- 
phuric acid were included, whereas in this paper only the true starch 
as determined by the diastase method is given. 
VARIATIONS IN PLANTS FROM IRRIGATED AND UNIRRIGATED HILLS 
Two adjacent plats at the station were planted with canna and 
irrigated until sprouting occurred. Irrigation was then discontinued 
on one plat, but continued every fifth day on the other. During the 
hot, dry summer which followed, the unirrigated plat produced a 
very stunted crop, whereas the plants on the irrigated plat made 
8 As previously stated (p. 2), the rootstock continues to increase in size, as was shown by actual 
measurements in the field and the occurrence of fresh cracks on the surface of rootstocks in old Groups 3a 
and 2. The phenomenon is noticeable particularly at Waimea. 
