1918] CURRENT LITERATURE 283 
incorrect in their conclusion that diastatic formation of maltose and transfer 
as such occurs in the case of the leaf of Tropaeolum. Brown and Morris 
unquestionably had maltose present, as shown by the fact that they obtained 
the osazone and that there was an increase in the reduction of copper after 
treatment with maltase, but the authors consider that this result may be 
explained by the fact that the material used by BRown and Morris was sub- 
jected to preliminary drying in an oven. They regard the leaf as having a 
mixture of enzymes analogous to that found in Aspergillus oryzae, and that 
it is therefore able to split maltose rapidly and completely to dextrose. They 
destroyed all enzymes instantly by dropping the leaves as they were picked into 
a mixture of boiling alcohol and ammonia. As maltase is easily destroyed by 
heating to 55°, it was first to go out of action in BRowN and Morris’ oven-dried 
material, while other more heat-resistant enzymes went on forming maltose 
which was not split up, hence was found in the analysis. This hypothesis is 
borne out by the results; Davis and SaAwveEr invariably found more starch in 
the leaves than did Brown and Morris, the amount always exceeding the sum 
of starch plus maltose found by the last-named authors. KLuyver employed 
a biochemical method, using Torula monosa to ferment the hexoses only, 7. 
dattilla to ferment the cane sugar and hexoses, leaving maltose, and found very 
small amounts of maltose. 
The authors consequently believe that starch degradation g 
down to hexoses with no stop at maltose; that plants must reduce sugars to this 
form before they can be utilized; and that the fact that the sugar in leaf stalks 
is largely hexose is thus explained, as is the presence of invertase in almost all 
plant parts. Dats found maltase wherever starch is found in leaves, but 
believes it to be an intracellular enzyme occurring in close proximity to diastase, 
hence never found in the vessels of the stalks. 
In the leaf saccharose is always greatly in excess of hexoses; in the stalks 
the reverse is always true. Hence saccharose must be the first product of 
photosynthesis and hexose a translocation form. The authors are led by 
unpublished work with a variety of other plants, such as sunflower, grape, and 
snowdrop, to the conclusion that this is the general situation with all plants 
regardless of the form in which final storage may occur. Like the potato, the 
plants just mentioned have two optically active impurities which are formed 
at different periods in the 24 hours, and hence have apparent large fluctuations 
in the dextrose-levulose ratio, which it is impossible to measure correctly by 
reason of their presence. 
The authors found in the leaves considerable amounts of dextro-rotatory, 
water-soluble material which was not soluble starch or dextrin, which was 
greatest in amount between 4 and 8 p.m. Its period of greatest formation 
synchronizes with the high tide of saccharose and the period of most rapid 
starch formation, hence it seems to be intermediate between the hexoses and 
true starch. Starch is very rapidly reduced after sunset, then more slowly 
with the hexoses rising, while the starch rises again at dawn considerably before 
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