MESSMATES, MUTUALISTS, AND PARASITES 93 
(Galanthus nivalis, fig. 1083). Here the smooth flower-stalk is 
bent over, so that the flower hangs down, and a creeping insect 
trying to reach it is almost certain to fall when it reaches the 
sharp bend. The nectar secreted in the green grooves of the 
petals is intended for flying insects. If 
one of these approaches from’ below it 
will first touch the stigma, effecting polli- 
nation if it has previously visited another 
snowdrop. And in getting the nectar it 
is sure to jolt the stamens, causing a 
shower of pollen to fall on its back, ready 
for transfer to other blossoms. 
A more drastic method of dealing 
with creeping insects is found in many 
plants which exude a sticky fluid, espe- _Fig: 1083.—Flower of Snowdrop 
; : . (Galanthus nivalis) 
cially in the neighbourhood of the flowers, 
or actually upon them. Sometimes this is of the nature of latex, 
as in the Lettuce (Lactuca sativa), where the flower-heads are 
surrounded by overlapping scales from which the milky secretion 
readily escapes, quickly coagulating into a sticky mass that catches 
and smothers ants and the like. The flower-stalks of Catch-Flies 
(see p. 86) and various other forms are 
covered by a glutinous layer, to which the 
bodies of trespassers are often found ad- 
hering. But more commonly the secretion 
is poured out by variously-situated glan- 
dular hairs. In Plumbago, for instance 
(fig. 1084), they are borne on the calyx. 
It would appear that in some instances the 
captured insects are used as food, after the J 
fashion of the carnivorous plants already Fig. 1084.—Flower of Plumbago 
: Europea (enlarged), showing glan- 
described (see p. 68). dioline Unis on Vhesealpe 
So far we have dealt with the exclusion 
of wingless insects, but in the case of large flowers evolved in 
relation to bees, wasps, butterflies, &c., small-winged insects are 
equally undesirable visitors, since they steal nectar without 
effecting cross-pollination. Such forms are altogether excluded, 
or else made effective by arrangements in ‘the flowers, which 
Kerner thus describes in general terms (in Zhe Natural Ffistory 
of Plants):—* Peculiar folds and cushions, walls and gratings, 
