at shall touch
them. A glance at the two views of this central portion of the flower,
as it appears through my magnifying-glass--the honey-horns and sepals
having been removed--will, I think, indicate its peculiar anatomy or
mechanism. No _stigma_ is to be seen in the flower, the stigmatic
surface which is to receive the pollen being concealed within five
compartments, each of which is protected by a raised tent-like covering,
cleft along its entire apex by a fine fissure (A). _Outside of each of
these, and entirely separated from the stigma in the cavity_, lie the
pollen masses within their pockets, each pair uniting at the rim below
in V-shape, the union at the lower limit of the fissure.

[Illustration]

[Illustration]

With this more intimate knowledge of the floral anatomy, let us now
visit our milkweed-plant and observe closely.

A bee alights upon the flower--the object of its visit being, of course,
the sweets located in the five horn-shaped nectaries. In order to reach
this nectar the insect must hang to the bulky blossom. Instantly, and
almost of necessity, it would seem, one or more of the feet are seen to
enter the upper opening of the fissure, and during the insect's
movements are drawn through to the base. The foot is thus conducted
directly between the two viscid discs, which immediately cling closer
than a brother, and as the foot is finally withdrawn, the pollen is
pulled from its cell. The member now released seeks a fresh hold, and
the same result follows, the leg almost inevitably entering the fissure,
and this time drawing in the pollen directly against the sticky
stigmatic surface within. The five honey-horns have now been drained,
and as our bee leaves the flower he is plainly detained by this too
hearty "shake" or "grip" of his host, and quite commonly must exert a
slight struggle to free himself. As the foot is thus forcibly torn away,
the pollen mass is commonly scraped entirely off and retained within the
fissure, or perhaps parts at the stalk, leaving the terminal disc
clinging on the insect's leg. Occasionally, when more than one leg is
entangled, the dangling blossom is tossed and swayed for several seconds
by the vigorous pulling and buzzing, and a number of these temporary
captives upon a single milkweed-plant are always to be seen.

Not unfrequently the mechanism so well adapted exceeds its functions and
proves a veritable trap, as indicated in my specimens. I have found
three dead