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Datura Metel L., D. Stramonium L. 
The water-calyces of some other Solanaceae have been described 
by Lagerheim and by Koorders viz. Jochroma macrocalyx Benth., 
Nkandra physaloides Gartn, and Juanulloa parasitica RuizetPav.; 
the very large flower-buds of Solandra grandijlora are also always 
filled with a considerable depth of water. Similarly it may be said • 
of the genus Datura that the corolla, stamens and ovary are developed 
in a water-containing calyx. Although the secretion of water in the 
species of this genus is not so abundant as in Solandra grandiflora 
or even in Nicandra physaloides, still a not inconsiderable quantity 
of water may always be found in the buds, and also later, during 
the flowering-period. But, whereas in other Solanaceae the water is 
secreted on the inner surface of the calyx, we find in Datura the 
peculiar modification, that the glands cover the outside of the corolla, 
whereas the inner surface of the calyx, while having many stomata, 
bears neither glands nor other trichomes. Nor is the glandular outer 
surface of the corolla free from stomata. In external shape and in 
internal structure these glands agree fairly well with those which 
are found in other Solanaceae; the secreting part in the glands 
of Datura also consists of three layers, but generally the middle 
cell is divided vertically in two, so that the glands are spherical 
rather than elliptical. In Datura Metel these waterglands are 
hidden between numerous long pointed hairs consisting of three or 
four cells. 
In other plants with water-calyces, the calyx shows a much 
more advanced growth and earlier development than the other parts 
of the flower, so thaf when the calyx already forms a fairly consi¬ 
derable space filled with water, the other floral organs only just begin 
to appear on the thalamus. In Datura, however, this is not the case. 
In very young buds of 3 mm. the corolla has already" a length of 
17s mm. and at this stage the water-glands are first formed. 
When the corolla has reached a length of 5 mm. it is covered 
from top to bottom, and especially on the teeth of the limb* with 
glands of various sizes in various stages of development. 
The outside of the calyx of Datura bears glands of approximately 
die same structure as those on the outside of the corolla and the 
applies to the peduncle. 
Further the leaves are covered on both sides, from their earliest 
youth, with glands which only differ from the glands of the corolla 
ln a subsidiary character i. e. the shape of the secreting part. In 
somewhat older leaves, which are already more or less unfolded, 
-frmy are. especially numerous and closely packed on both surfaces 
