The pollen-grains have remarkably thin transparent coats;
when exposed to the air they shrivel up quickly; when placed in water they
swell, and are then 8-10/7000 of an inch in diameter, and therefore of smaller
size than the ordinary pollen-grains similarly treated, which have a diameter of
13-14/7000 of an inch. In the cleistogamic flowers, the pollen-grains, as far as
I could see, never naturally fall out of the anther-cells, but emit their tubes
through a pore at the upper end. I was able to trace the tubes from the grains
some way down the stigma. The pistil is very short, with the style hooked, so
that its extremity, which is a little enlarged or funnel-shaped and represents
the stigma, is directed downwards, being covered by the two membranous
expansions of the antheriferous stamens. It is remarkable that there is an open
passage from the enlarged funnel-shaped extremity to within the ovarium; this
was evident, as slight pressure caused a bubble of air, which had been drawn in
by some accident, to travel freely from one end to the other: a similar passage
was observed by Michalet in V. alba. The pistil therefore differs considerably
from that of the perfect flower; for in the latter it is much longer, and
straight with the exception of the rectangularly bent stigma; nor is it
perforated by an open passage.
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