8 
BULLETIN 56, HAWAII EXPERIMENT STATION 
Ethyl alcohol, used in the proportion of 2 parts to 1 of sap, pre- 
vented changes in the sugars. The sugars largely disappeared in the 
untreated sap. Since, as the results show, it is not necessary to filter 
off the alcohol precipitate before storage, 50 cubic centimeters of 
alcohol was pipetted into 4-ounce glass-stoppered bottles in the lab- 
oratory for use in the field. Samples of the canna plant were col- 
lected and 25 cubic centimeters of the sap was, in each instance, 
expressed and pipetted 
into the containers in 
the field. 
DETERMINATION OF STARCH 
Starch was deter- 
mined in the dry samples 
by the diastase method 
recommended by the 
Association of Official 
Agricultural Chemists 
(1, p. 95), the resultant 
sugars being determined 
by the method of Mun- 
son and Walker (1, p. 
78). 
The specific gravity 
of therootstockswas de- 
termined by the West- 
phal balance, kerosene 
being used as the immer- 
sion medium. The use 
of water was not feasi- 
ble because 4;he differ- 
ence in its density and 
that of the canna root- 
stock is too small. The 
latter sometimes has a 
specific gravity less than 
water. Kerosene, with 
a density of 0.815 at 
room temperature, gives 
a convenient difference 
in density, and has the 
additional advantage 
that it causes portions 
of the sap exuding from 
the cut surfaces of the 
rootstock to precipitate undissolved to the bottom of the container. 
The rootstock was suspended by means of a fine wire connected with 
a small screw driven into the rootstock. All roots, dead scales, and 
adhering soil, as well as the stem, were carefully removed from the 
rootstock before determination was made. The removal of the stem 
at the exact apex of the rootstock is important since the specific grav- 
ities of the stem and the apical and basal parts of the rootstock are 
Fig. 6. — Two generations of "spike" rootstocks produced from a 
single stem. A, the second generation, is developing its stem. 
The meristem of B, the first generation, was killed. The upper 
part of the parent stem was removed 
