CAENIVOEOITS PLANTS. 
353 
pretty little Drosera , or Sundew, a denizen of bogs, with its 
small red leaves clothed with glands which are apparently 
always wet with dew on the hottest summer day, and elegant 
scape of minute white flowers, opening only in the brightest 
sunshine. The commonest species D. rotundifolia, with round 
leaves, is found in sphagnum and peat-bogs throughout the 
country, and is especially common in all our sub-alpine districts. 
Two other species are British, D. intermedia and anglica , both 
with linear-oblong leaves, the latter much the larger plant, but 
are much scarcer ; the former, however, grows as near London as 
close by the Burnham Beeches in Buckinghamshire, intermixed 
with D. rotundifolia , and is abundant in the New Forest. On 
closer examination it is seen that the minute drops which hang 
on the glands are not dew, but consist of a viscid fluid stretched 
in threads from one to another ; and that numbers of minute 
insects are captured in it and firmly held down by the enfolding 
of the glands over them. 
The leaf is indeed a veritable fly-trap. If a specimen is planted 
in a saucer in damp sand, and a minute insect placed on a leaf 
which was before quite free, the glands will be seen to bend 
over it, commencing with the ones nearest to those that actually 
touch it, until at length every gland on the leaf has become in- 
flected, and the insect is hopelessly imprisoned. Long before 
this it has, however, probably almost ceased to move ; and that 
the movement of the glands is not the result of mechanical irri- 
tation from the struggles of the insect — like that of the stamens 
of Berberis — is proved by the fact that the outermost marginal 
glands do not fold over until the struggles of the insect have 
ceased. Fig. 1, Plate CXXVI., shows a plant of Drosera ro- 
tundifolia about the natural size ; fig. 2, one of the leaves 
magnified about twice; fig. 3, a leaf with an insect just cap- 
tured ; fig. 4, one in which nearly all the glands are folded 
over, both multiplied about four times ; and fig. 5, one of the 
glands on a much larger scale. 
The mechanism of the movement of the “tentacles,” as 
Darwin terms these organs, has been closely investigated by him 
and others. Each tentacle consists of a stalk or pedicel, com- 
posed of several rows of elongated cells, with a roundish or 
ellipsoidal dark-red gland at its extremity. The gland is seen 
under a high magnifying power to be pitted or honeycombed ; 
and the pedicels, as well as the upper surface of the leaf where 
not occupied by the tentacles, is provided with a number of 
minute papillae, consisting of several cells. The morphological 
nature of the tentacles has been a subject of much discussion. 
Trecul, Warming, and other observers have clearly shown that, 
at least as regards some of them, especially those at or near the 
margin of the leaf, they are an integral part of the leaf itself, 
VOL. XXV. — NO. LVII. A A 
