Latex and its Functions . 
201 
results indicated most sugar in the latex which first trickled 
from the wounds, suggesting that the latex in oozing out had 
carried with it saccharine sap from the surrounding injured 
cells. 
Biffen 1 has shown that the amount of sugar in latex is 
more in that collected from the plant in the late afternoon 
than in that in the early morning, the inference being that 
the laticiferous tubes receive the sugar arising from assimila¬ 
tion. Considering that the quantity is small, on an average 
about i*5 grams of glucose per iooc.c. of latex, it is quite 
possible that a considerable portion may have come from 
the adjacent injured tissues, such as the parenchyma and 
phloem-elements. 
One of the most peculiar features connected with latex 
is the occurrence of the well-known rods of starch in the 
laticiferous tubes of Euphorbia and allied genera. Does it 
mean that these tubes serve as channels for the conduction 
in a solid form of the carbohydrate elaborated in the leaf? 
It is an attractive view, and one which received a certain 
amount of support from the work of Treub 2 some years ago. 
He found that after darkening portions of the stems of 
succulent species of Euphorbia , the starch-rods had wholly 
or largely disappeared from the darkened areas. His results, 
however, are somewhat vitiated by the long duration of the 
darkening—three to five weeks. 
Schimper’s 3 experiments, on the other hand, show that 
the laticiferous tubes are not depleted of their starch in the 
dark. He found that the darkening of the leaves of Euphorbia 
Peplus , E. Lathyris , and E. heterophylla made, as a rule, no 
appreciable difference in the starch in the milk-tubes, whereas 
the starch disappeared wholly from the mesophyll of the leaf. 
He also incidentally mentions the fact that the dead leaves 
of E. Lathyris and E. Myrsinites have their tubes still full 
of starch. 
1 Biffen, Annals of Botany, xi, 1897, p. 338. 
2 Treub, Ann. du Jardin Bot. de Buitenzorg, iii, 1883, p. 39. 
3 Schimper, Bot. Zeit., 1885, pp. 771-779. 
