2 a. Anther. s. Stigma.]

Many of our common wild flowers, as perfectly and effectually planned
for cross-fertilization as the orchids, _do_ retain the reserve power of
final _self_-fertilization if unfertilized by foreign pollen.

But the orchid has lost such power, and in the progress of evolution has
gradually adapted itself to the insect, often to a particular species of
insect, its sole sponsor, which natural selection has again gradually
modified in relation to the flower.

The above work by Darwin was mostly concerned with foreign species,
generally under artificial cultivation, and so startling were the
disclosures concerning these hitherto sphinx-like floral beings that a
most extensive bibliography soon attested the widespread inspiration and
interest awakened by its pages.

But it is by no means necessary to visit the tropics or the conservatory
for examples of these wonders. Our own Asa Gray, one of Darwin's instant
proselytes, was prompt to demonstrate that the commonest of our native
American species might afford revelations quite as astonishing as those
exotic species which Darwin had described.

[Illustration: Fig. 3]

During a period of many years the writer has devoted much study to our
native species of orchids from this evolutionary stand-point of their
cross-fertilization tendencies. Of the following examples, selected from
his list, some are elaborations of previous descriptions of Gray and
others, though pictorially and descriptively the result of direct
original study from nature; others are from actual observation of the
insects at work on the flowers; and others still, original
demonstrations based upon analogy and the obvious intention of the
floral construction, the action of the insect--its head or
tongue--having been artificially imitated by pins, bristles, or other
probe-like bodies.

How many an enthusiastic flower-hunter has plucked his fragrant bouquet
of the beautiful Arethusa, in its sedgy haunt, without a suspicion of
the beautiful secret which lay beneath its singular form! Indeed, how
many a learned botanist, long perfectly familiar with its peculiarities
of shape and structure, has been entirely content with this simple fact,
nor cared to seek further for its interpretation! But

"All may have the flower now,
For all have got the seed."

With Darwin as our guide and the insect as our key--an _open
sesame_--the hidden treasure is revealed. It is now quite possible, as