PLANTS DEFEND THEMSELVES 39 
bee, on a honey-gathering trip, attracted by the 
brilliant touch of colour at the tip of the blossom, 
alights on the end of the lower petal, his weight 
bears it down, opening the door, and he walks in 
and has his feast, incidentally brushing the pollen 
as he passes. 
This means of protection—the shape of the 
flower—is only one of many means followed by 
various plants. Every observant person has no- 
ticed the glossy, varnish-like stems which some 
plants have. This varnish-covering is another 
means of defence utilised by the ingenious plants. 
That surface with its glossy sheen presents a foot- 
ing far too slippery for any of the nimble-footed 
ants and their kin to ascend; and so against such 
incursions the honey-well is secured. The catkins 
of the willow show this condition admirably: over 
their surfaces is temptingly displayed a nectar, 
so sweet and seductive that winged pollen-bearers 
are attracted from all directions to the enjoyment 
of the repast, but this same exudation renders the 
stem so slippery and impassable that the grasping 
wingless insect cannot ascend. 
Another very common defence against the crawl- 
ing pest is a sticky glue, which, instead of allow- 
ing the marauding intruder to slip back, holds him 
fast, a prisoner dying in sight of the joys that have 
