379 
of locating Sugars in Plant Tissties. 
passed even after six months, while in higher concentrations crystals may 
appear in a day or two, or even within a few hours if the heating is more 
prolonged. 
Considerable caution must therefore be exercised in attempting to 
locate maltose in starch-forming plants by means of Senft’s reagent. The 
formation of drops of syrupy liquid within cells, especially if in any 
quantity, and if in tissues examined after starch dissolution is known to 
have occurred, in all probability denotes the presence of maltose, though 
other possibilities are not altogether excluded. 1 
If actual crystals are formed the osazone can be identified with less 
uncertainty, though here again it is necessary to bear in mind alternative 
interpretations. 2 
Here it may be remarked that the failure of Strakosch to detect 
maltose regularly in the leaves of the beet, and his finding of only small 
quantities in the petiole, 3 may perhaps have been caused partly by the 
failure of the osazone to crystallize in glycerine. 
The effect of glycerine upon the crystallization of the osazones was 
further investigated by mixing the latter with glycerine in various propor¬ 
tions, heating the mixtures, and allowing them to cool prior to examining 
them microscopically. 
Experiment III. Levulose and dextrose phenylosazones were added 
to pure glycerine so as to give o-i per cent., i*o per cent., and 5 per cent, 
mixtures. The tubes containing these were then heated and shaken until 
the contents appeared homogeneous. The colour of the resulting liquid 
varied from straw to dark brown according to the concentration of the 
osazone. 
Drops were mounted immediately after heating and mixing, and were 
examined microscopically at once. 
The results obtained are shown in the table below. 
When 
examined. 
Levulose. 
Dextrose. 
Just after 
Tubes. o*i % Clear straw-coloured liquid. 
Tubes, o-i % Clear straw-coloured liquid. 
heating. 
i*o% Dark-brown liquid deposit¬ 
ing crystals on cooling 
and setting stiffly. 
i-o % As with levulose. 
5-0 % Yellowish-brown solid 
mass on cooling. 
5-0 % As with levulose. 
Slides, o-i % Showed beginnings of 
crystal formation within 
an hour. 
Slides. 0.1 % Much as with levulose. 
i*o% Deposited crystals within 
a few minutes of mount¬ 
ing. Well formed after 
20 minutes. 
1.0 % Much as with levulose. 
1 See below, p. 387. 
2 See below, p. 387 
3 Strakosch, 1 . c., p. 863. 
Cca 
