28 
HOW PLANTS EMPLOY INSECTS TO WORK FOR THEM, 
the honey-tube, its mouth opening just behind the base of this petal. Only the 
lower half of the tube, more enlarged and capacious, gets filled with nectar. To 
drain a cup which is about an inch and a half 
deep requires a long proboscis, much longer 
than any bee or w T asp possesses. Butterflies 
and moths are our only insects capable of do- 
ing it ; and one could predict from a view of 
the flower that the work is done by them. In 
fact we have hardly a butterfly with proboscis 
long enough to reach the bottom of the cup : 
so. we conclude that one of the Sphynxes or 
Night-moths, such as flock around the blos- 
soms of the largest Evening-Primroses at dusk, 
is the proper helpmate of the Greater Green 
Orchis. The Smaller Green Orchis is much 
like the Larger, but with honey-tube hardly an 
inch long. This may be drained by many of 
our butterflies. Some of these have been 
caught wflth a remarkable body attached to 
their great eyes, one on each eye ; on exam- 
ination this body proved to be quite like that 
represented in Fig. 18, only smaller. This 
body, as we have seen, is the pollen of one 
of the cells of an Orchis anther, with its 
stalk and sticky disk, the latter adhering to 
the insect’s eye. How did it get there 1 
57. The centre of the flower (as in Fig. 
16) is occupied by the one large anther, and 
by the concave stigma. The anther is of 
two cells, which taper towards the front of 
the flower and diverge, in this species widely, and the whole space between the 
two diverging horns on the sides and the orifice of the honey-tube below is stigma, 
a broad patch of glutinous surface. At the tip of each horn of the anther, facing 
forwards and partly inwards is the button-shaped, sticky disk. Bring the point 
of a blunt pencil, or the tip of the little finger, or anything of the proper size, 
Fig. 20. Side view of head of a moth (Sphynx 
drupiferarum), which has just extracted a 
pair of Orchis pollen-masses. 
Fig. 31. Front view of the same, with the pollen- 
masses in the position they soon take. Both 
figures magnified to the same degree as is the 
Orchis flower in Fig. 16. 
