The two lobes stand at rather less than a right angle to each other.
Three minute pointed processes or filaments, placed triangularly,
project from the upper surfaces of both; but I have seen two leaves
with four filaments on each side, and another with only two. These
filaments are remarkable from their extreme sensitiveness to a touch,
as shown not by their own movement, but by that of the lobes. The
margins of the leaf are prolonged into sharp rigid projections which I
will call spikes, into each of which a bundle
FIG. 12. (Dionaea muscipula.) Leaf viewed laterally in its expanded
state.
of spiral vessels enters. The spikes stand in such a position that,
when the lobes close, they inter-lock like the teeth of a rat-trap. The
midrib of the leaf, on the lower side, is strongly developed and
prominent.
The upper surface of the leaf is thickly covered, excepting towards the
margins, with minute glands of a reddish or purplish colour, the rest
of the leaf being green. There are no glands on the spikes, or on the
foliaceous footstalk, The glands are formed of from [page 288] twenty
to thirty polygonal cells, filled with purple fluid. Their upper
surface is convex. They stand on very short pedicels, into which spiral
vessels do not enter, in which respect they differ from the tentacles
of Drosera. They secrete, but only when excited by the absorption of
certain matters; and they have the power of absorption. Minute
projections, formed of eight divergent arms of a reddish-brown or
orange colour, and appearing under the microscope like elegant little
flowers, are scattered in considerable numbers over the foot-stalk, the
backs of the leaves, and the spikes, with a few on the upper surface of
the lobes. These octofid projections are no doubt homologous with the
papillae on the leaves of Drosera rotundifolia. There are also a few
very minute, simple, pointed hairs, about 7/12000 (.0148 mm.) of an
inch in length on the backs of the leaves.
The sensitive filaments are formed of several rows of elongated cells,
filled with purplish fluid. They are a little above the 1/20 of an inch
in length; are thin and delicate, and taper to a point. I examined the
bases of several, making sections of them, but no trace of the entrance
of any vessel could be seen. The apex is sometimes bifid or even
trifid, owing to a slight separation between the terminal pointed
cells. Towards the base there is constriction, formed of broader cells,
beneath which there is an articulation, supported on an enlarged base,
consisting of differently shaped polygonal cells. As the filaments
project at right angles to the surface of the leaf, they would have
been liable to be broken whenever the lobes closed together, had it not
been for the articulation which allows them to bend flat down.
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Elsewhere in the archive
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account