166 Detection of Maltose in Tissues of Angiosperms. 
of these crystals in longitudinal sections of the veins of various 
starch-forming dicotyledonous leaves, viz. Helianthus animus, 
Cucurbita Pepo , Phaseolus cerasiftorus, Physatis Alkekengi, and 
in the stem of Urtica dioica. The crystals occur in detached, 
dense masses in the assimilating cells, the phloem of the vascular 
bundles and in the nerve parenchyma. They are very obvious 
when viewed through the microscope as opaque objects, owing to 
their light yellow colour. 
In connection with various anatomical considerations and 
experimental results, which have indicated that sugars are translo¬ 
cated from the leaf in the sieve-tubes, 1 it is interesting to note the 
very close association of these crystal masses with sieve-tubes. In 
such cases the sieve-tubes themselves are often lined with an 
orange-coloured liquid like that from which the crystals of maltose 
phenylosazome are formed. The masses of crystals appearing at 
intervals in close contact with the sieve-tubes seem to have been 
produced from some of the syrupy contents of the sieve-tubes. 
That crystals do not regularly appear within the sieve-tubes maybe 
due to the confined space, for in Cucufbitap where the diameter of 
these elements is large, crystals have been observed inside them 
(Fig. 4). Thus direct evidence is furnished of the presence of 
maltose in the sieve-tubes of the Cucurbita under conditions when 
translocation was known to be going on. 
The close association of the crystals with the sieve-tubes in the 
other plants, and the presence within them of the yellow syrup, 
suggest that in these cases also maltose travels as such in the 
sieve-tubes. 3 Doubtless it becomes hydrolised, en route, by enzymes 
present in the sieve-tubes or excreted by the companion cells, as 
is suggested by the fact that while the distal ends of the sieve- 
tubes often contain only the yellow syrup, towards the proximal 
ends a more definitely crystalline content is to be observed. This 
is particularly the case with Helianthus animus, where the crystals 
resemble those given by dextrose, although this sugar is not 
necessarily present only as the result of the hydrolysis of maltose. 
1 cf. Mangham, S. “ The translocation of carbohydrates in 
plants.” Science Progress, Oct. 191£), Jan. 1911. 
2 The leaf had been darkened for some days. 
3 cf. Brown and Morris. “A contribution to the Chemistry and 
Physiology of Foliage Leaves.” Journ. Chem. Soc., 1893, 
p. 673. 
