of locating Sugars in Plant Tissues. 385 
cellular experiments will hold good for reactions carried out inside plant 
cells, for it is impossible to realize the precise conditions obtaining in the 
latter. Still it may be urged that the above results and considerations 
afford some justification for regarding as maltose phenylosazone the yellow 
syrup so often observed inside cells (especially the sieve-tubes of fine veins 
in leaves) after treating with Senft’s reagent sections of veins, petioles, &c., 
taken from starch-forming leaves which had previously been placed under 
conditions ensuring hydrolysis of starch and translocation of sugar. 
Furthermore, it may be suggested that the production of an apparently 
homogeneous syrup in these cells probably indicates the presence of maltose 
alone, 1 while the appearance which has been recorded in notes of experi¬ 
ments as ‘ semi-crystalline ’, ‘ amorphous ’, or ‘ granular ’, and which has been 
found on the whole less commonly in the sieve-tubes of the finer veins of 
leaves than in those of the stronger ones, would then denote either maltose 2 
from which osazone crystals had formed (or were forming) and were mingled 
with some uncrystallized syrup, or a mixture of maltose with other sugars. 
For example, such an appearance might well be produced if maltose, 
in the course of translocation, gradually became hydrolysed under the action 
of maltase produced by the sieve-tubes themselves or by the companion- 
cells, 3 or if hydrolysis occurred during the heating of the preparations. 4 
The resulting dextrose would yield osazone crystals, but there would 
probably be some syrup as well if any maltose remained, and in the con¬ 
fined space of the sieve-tubes the two would be obliged to mix to a certain 
extent. 
Again, if in addition to maltose cane sugar had entered the sieve-tubes, 
and sufficient of it had become hydrolysed either during the heating or 
previously while undergoing translocation, a deposit of crystalline osazone 
might be formed and so produce the appearance referred to. 
Finally, there might also be present with the maltose before treatment 
with the reagent hexoses which had not arisen from the hydrolysis of bioses. 5 
Reaction with Mixtures of Sugars. 
It was remarked above that the presence of other sugars may influence 
the osazone reaction given by any particular sugar. 
In this connexion considerable interest attaches to the work of Scher- 
man and Williams, 6 who studied the rate of precipitation of osazones from 
aqueous solutions of one or more sugars. Other conditions being un¬ 
changed, they found that the rate of precipitation with dextrose varied with 
1 Probably in low concentration. 2 Probably in higher concentration. 
3 Cf. Scott (’ 89 ), p. 156. 4 Cf. above, p. 377. 
6 In this connexion cf. Brown and Morris (’ 93 ), Strakosch, 1 . c., Parkin (’ll), Ruhland, 1 . c., 
Campbell (’12), and Armstrong, 1 . c. 
6 Scherman and Williams (’ 06)1 
