Such, with slight modifications, is the plan evolved by the whole
cypripedium tribe. Darwin mentions bees as the implied fertilizers, and
doubtless many of the smaller bees do effect cross-fertilization in the
smaller species. But the more ample passage in acaule would suggest the
medium-sized Bombus as better adapted--as the experiment herewith
pictured from my own experience many times would seem to verify, while a
honey-bee introduced into the flower failed to fulfil the demonstration,
emerging at the little doorway above without a sign of the cordial
parting token.

[Illustration: Fig. 18 B]

Occasionally I suppose a fool bumblebee is entrapped within the petal
bower and fails to find the proper exit, or it may be--much less a
fool--having run the gantlet once too often, decides to escape the
ordeal; hence the occasional mutilated blossom already described.

One of the most beautiful of our orchids, though its claims to
admiration in this instance are chiefly confined to the foliage, is the
common "Rattlesnake-Plantain," its prostrate rosettes of exquisitely
white reticulated leaves carpeting many a nook in the shadows of the
hemlocks, its dense spikes of yellowish-white blossoms signalling their
welcome to the bees, and fully compensating in interest what they may
lack in other attractive attributes.

[Illustration: Fig. 18 C]

The single flower is shown enlarged in Fig. 19--A, a young blossom, with
analyses B and C, the latter indexed; D, an older blossom, with similar
analyses (E and F). Both sorts are to be found upon every spike of
bloom, as the inflorescence begins at the base and proceeds upward. As
we look into the more open flower we observe a dark-colored speck,
which, by analysis, proves to be the lid of the anther. This portion is
further shown enlarged in Fig. 20, A. If we gently lift it with a pin,
we disclose the pollen masses in the cavity (B) thus opened (C, profile
section), the two pairs united to a common viscid gland at the base,
this gland again secreted behind a veil of moist membrane, as also shown
at B. This membrane is, moreover, very sensitive to the touch. Below the
flattened tip of the column, and at a sharp inward angle, is the stigma.
In the freshly opened flower (Fig. 19, A) the column inclines forward,
bringing the anther low down, and its base directly opposite the
V-shaped orifice in the lip, which also is quite firmly closed beneath
the equally converging upper hood of th