1918] CURRENT LITERATURE 281 
in which top and bottom halves of petioles were not analyzed separately, 
saccharose was constant throughout the 24 hours; total hexoses and apparent 
levulose were least at 11 P.M., increased slowly to 4 A.M., then more rapidly until 
4 P.M., when they again declined together until 11 p.m. Apparent dextrose rose 
from 4 A.M. until 4 P.M., then remained stationary throughout afternoon and 
night. In the midribs, however, tetal hexoses decreased slowly from 10 A.M. 
to 4 P.M., then more rapidly through the night, rising again at 4A.M. Apparent 
levulose decreased, apparent dextrose increased, from 10 A.M. to 4 P.M., after 
which dextrose rather rapidly fell off while levulose slowly increased until 
4 A.M., when both began to increase. Saccharose was stationary from 10 A.M. 
to 4 P.M., then increased slowly and uniformly through the evening and night, 
beginning to fall at 4 a.m. There is, therefore, a steady movement of sugars 
from leaves to midribs, thence through the stalks, the maximum in leaves at 
2 A.M. moving onward into the stalks to give a maximum there at 6 A.M., which 
is succeeded by a minimum 4 hours later, when a large part of the sugar formed 
during the insolation of the preceding day has passed from stalk to root. The 
ratios of invert sugar to cane sugar at any given hour of the day, as at 6 A.M., 
September 10, when it is 1.48 in leaf, 3.32 in midrib, and 5.27 in stalk, are 
significant, showing as they do that there are progressively more and more 
hexoses in the stream of sugars as it passes from leaf to root. On August 26 
the stalks had at noon 4.25 per cent saccharose and 11.57 per cent hexose; 
at 10 A.M., September 10, 4.82 per cent saccharose and 20.5 per cent hexose; 
and at 11 A.M., October 11, 5.29 per cent saccharose and 25.7 per cent hexose. 
This is strong evidence that hexoses are translocation forms produced by the 
conversion of cane sugar, as is the fact that cane sugar greatly predominates in 
the leaves in the early stages of growth, prior to the beginning of storage in the 
roots. Further evidence is seen in the fact that cane sugar is the predominant 
sugar in the leaves of the potato, vine, and snowdrop, although these plants 
store carbohydrate as starch, dextrose, and inulin respectively, and do not store 
cane sugar. Cane sugar is therefore formed in the mesophyll, transported 
into the vessels, undergoes progressive inversion as it passes onward throug 
midribs and stalks, enters the roots as reducing sugars, and these are there 
transformed once more into saccharose. The authors have not studied the 
mechanism of this synthesis in the root; invertase was shown to be present in 
the sieve tubes but was not found in roots by ROBERTSON, IRVINE, and DoBson, 
and it is believed to be the agent in the inversion occurring during transport. 
Since the existence of the saccharogenic enzyme of BorDET has not yet been 
substantiated, and the probability of reversible zymohydrolysis by invertase 
is contra-indicated by the absence of invertase from the roots, the authors are 
unable to formulate a theory as to the agent responsible for this synthesis. 
In the second paper of the series Davis reports the result of a study of the 
msg ble ratio in the mangold. The determination of these sugars 
polarimetric methods is falsified by the presence of optically active sub- 
edhe not a by basic lead acetate.. Glutamine, glutaminic acid, 
