unt, the whole form of the
opening of the flower would seem to imply a bee, particularly a
bumblebee. If we insert the point of a lead-pencil into this opening,
thus imitating the entrance of a bee, its bevelled surface comes in
contact with the viscid discs by the rupture of a veil of membrane,
which has hitherto protected them. The discs adhere to the pencil, and
are withdrawn upon it (Fig. 9). At first in upright position, they soon
assume the forward inclination, as previously described. The nectary is
about the length of a bumblebee's tongue, and is, moreover, so amply
expanded at the throat below the stigma as to comfortably admit its
wedge-shaped head. The three progressive diagrams (Fig. 10) indicate the
result in the event of such a visit.

The pollen discs are here very close together, and are protected within
a membraneous cup, in which they sit as in a socket. As the insect
inserts his head at the opening (A) it is brought against this tender
membrane, which ruptures and exposes the viscid glands of the pollen
masses, which become instantly attached to the face or head, perhaps
the eyes, of the burly visitor. As the insect retreats from the flower,
one or both of the pollinia are withdrawn, as at B. Then immediately
follows a downward movement, which exactly anticipates the position of
the stigma, and as the bee enters the next flower the pollen clubs are
forced against it (C), as in the previous example.

[Illustration: Fig. 9]

In the case of a smaller bee visiting the flower, the insect would find
it necessary to creep further into the opening, and thus might bring its
thorax against the pollen-glands. In either case the change of position
in the pollinia would insure the same result.

[Illustration: Fig. 10 A B]

We have thus seen adaptation to the thorax, the eyes, and the face in
the three examples given. And the entrance of the flower in each
instance is so formed as to insure the proper angle of approach for the
insect for the accomplishment of the desired result. This direct
approach, so necessary in many orchids, is insured by various
devices--by the position of the lip upon which the insect must alight;
by the narrowed entrance of the throat of the flower in front of the
nectary; by a fissure in the centre of the lip, by which the tongue is
conducted, etc.

[Illustration: Fig. 10 C]

Many other species allied to the above possess similar devices, with
slight variations; and there is still