c 409 ) 
hairs of 3-4-cells, with highly refractive content; the distribution of 
these hairs is not determined by the veins. They no longer occur 
on the adult leaves. 
In a moist space Nicandra physaloides behaves exactly like 
Datura. 
After a few hours the young flowers and leaves — except the 
very youngest leaves of the bud — are covered with a layer of 
water, while the conical hairs show themselves to be mucilage- 
glands. The mucilage-secretion is slight, however; small droplets 
only occur, on a few hairs. This is not only observed in a moist 
space, but also on young plants, cut off and placed in a glass of 
water, but not covered by a bell-jar. Finally we may also observe 
in the moist space that the glands on the lower surface of the corolla 
secrete water during the flowering period, as was mentioned above. 
Dahlia spec, et var. div. 
As long as the capitula of Dahlia are still in the bud, the youngest 
florets are covered by the inner bracts of the involucre. Generally 
we may easily observe at this stage, that the hanging capitula 
are moist below, and that drops of liquid, between the involucral 
bracts and the florets, are discernible through the translucent bracts 
and may be moved to and fro by the slight pressure of a lead-pencil. 
Not infrequently a drop of liquid may also be seen hanging down 
from the capitulum, especially when the sky is overcast. 
The droplets consist of water. 
This secretion of water, although not inconsiderable, is much 
greater after fertilisation. The capitulum, which had opened out 
during the flowering period, once more closes up, while the invo¬ 
lucral bracts grow considerably. The capitulum after flowering assumes 
the shape of a hanging top. 
At the apex of the top a drop of water can nearly always be 
observed during the whole period of the ripening of the fruits; after 
removal this drop is renewed, in proof that water is continually 
excreted Somewhere in the capitulum. 
Further investigation shows that all ovaries and all corollae in 
the capitulum are covered on the outside with long trichomes, con¬ 
sisting of a row of about 15 cells with dense content, and reminding 
0ne of the nectar-secreting glands of Malvaceae. These trichomes 
are the glands which secrete the water. 
In Dahlia every floret is placed in the axil of a bract. This 
Pact completely enclosing the flowerbud, does not bear glands or 
ther trichomes and does not take part in the secretion of water. 
Proceedings Royal Acad. Amsterdam. Vol. XU. 
