h only. Hence
we infer the sphinx-moth to be the insect complement to the blossom, and
we may correctly infer, moreover, that the flower is thus a
night-bloomer. Examination of the flower, with the form of this moth in
mind, will show other adaptations to the insect's form in the position
of pollen and stigma, looking to the flower's cross-fertilization. In
some cases this is effected by the aid of the insect's tongue; in
others, by its eyes.

In our own native orchids we have a remarkable example of the latter
form in the _Habenaria orbiculata_, whose structure and mechanism have
also been admirably described by Asa Gray.

[Illustration: Fig. 5]

All orchid-hunters know this most exceptional example of our local
flora, and the thrill of delight experienced when one first encounters
it in the mountain wilderness, its typical haunt, is an event to date
from--its two great, glistening, fluted leaves, sometimes as large as
a dinner-plate, spreading flat upon the mould, and surmounted by the
slender leafless stalk, with its terminal loose raceme of greenish-white
bloom.

[Illustration]

A single blossom of the species is shown in Fig. 5, the parts indexed.
The opening to the nectary is seen just below the stigmatic surface, the
nectary itself being nearly two inches in length. The pollen is in two
club-like bodies, each hidden within a fissured pouch on either side of
the stigma, and coming to the surface at the base in their opposing
sticky discs as shown. Many of the group Habenaria or Platanthera, to
which this flower belongs, are similarly planned. But mark the
peculiarly logical association of the parts here exhibited. The nectary
implies a welcome to a tongue two inches long, and will reward none
other. This clearly shuts out the bees, butterflies, and smaller moths.
What insect, then, is here implied? The sphinx-moth again, one of the
lesser of the group. A larger individual might sip the nectar, it is
true, but its longer tongue would reach the base of the tube without
effecting the slightest contact with the pollen, which is of course the
desideratum here embodied, and which has reference to a tongue
corresponding to the length of the nectary. There are many of these
smaller sphinxes. Let us suppose one to be hovering at the blossom's
throat. Its slender capillary tongue enters the opening. Ere it can
reach the sweets the insect's head must be forced well into the throat
of the blossom, where we now observe