secondly, the power possessed by the leaves of rendering soluble or
digesting nitrogenous substances, and of afterwards absorbing them;
thirdly, the changes which take place within the cells of the
tentacles, when the glands are excited in various ways.
It is necessary, in the first place, to describe briefly the plant. It
bears from two or three to five or six leaves, generally extended more
or less horizontally, but sometimes standing vertically upwards. The
shape and general appearance of a leaf is shown, as seen from above, in
fig. 1, and as seen laterally, in fig. 2. The leaves are commonly a
little broader than long,
FIG. 2. (Drosera rotundifolia.) Old leaf viewed laterally; enlarged
about five times.
but this was not the case in the one here figured. The whole upper
surface is covered with gland-bearing filaments, or tentacles, as I
shall call them, from their manner of acting. The glands were counted
on thirty-one leaves, but many of these were of unusually large size,
and the average number was 192; the greatest number being 260, and the
least 130. The glands are each surrounded by large drops of extremely
viscid secretion, which, glittering in the sun, have given rise to the
plant s poetical name of the sun-dew.
[The tentacles on the central part of the leaf or disc are short and
stand upright, and their pedicels are green. Towards the margin they
become longer and longer and more inclined [page 5] outwards, with
their pedicels of a purple colour. Those on the extreme margin project
in the same plane with the leaf, or more commonly (see fig. 2) are
considerably reflexed. A few tentacles spring from the base of the
footstalk or petiole, and these are the longest of all, being sometimes
nearly 1/4 of an inch in length. On a leaf bearing altogether 252
tentacles, the short ones on the disc, having green pedicels, were in
number to the longer submarginal and marginal tentacles, having purple
pedicels, as nine to sixteen.
A tentacle consists of a thin, straight, hair-like pedicel, carrying a
gland on the summit. The pedicel is somewhat flattened, and is formed
of several rows of elongated cells, filled with purple fluid or
9