have interpreted its structure: "How
simple and perfect the structure! Observe how the anthers are placed so
that pollen shall naturally fall directly on the stigmas and fertilize
them!" Such would indeed appear to be intended, until it is actually
discovered that the _stigmas have withered_ when the pollen is shed--a
device which, acting in association with the little ring of hairs, tells
a strange story. It is not my fortune to have seen one of these singular
blossoms, but from the description of the process of fertilization given
in Hermann Mueller's wonderful work, aided by a botanical illustration
of the structure of the flower, I am readily enabled to picture the
progressive stages of the mechanism.

[Illustration: Fig. 13]

In the first stage (B, Fig. 13) small flies with bodies dusted with
pollen from a previous arum blossom (for insects, as a rule, remain
faithful or partial to one species of flowers while it is in bloom) are
entering the narrowed tube, easily passing through the drooping fringe
of hairs. Nectar is secreted by the stigmas, and here the flies
assemble, thus dusting them with pollen. Their appetite temporarily
satisfied, the insects seek escape, but find their exit effectually
barred by the intruding fringe of hairs (C). In this second stage the
stigmas, having now been fertilized, have withered, at the same time
exuding a fresh supply of nectar, which again attracts the flies,
whereupon, as shown at D, the anthers open and discharge their pollen
upon the insects. In the fourth stage (E), all the functions of the
flower having now been fulfilled, the fringe of hairs withers, and the
imprisoned pollen-laden flies are permitted to escape to another flower,
where the beautiful scheme is again enacted.

In a paper of this kind it is of course possible only to hint at a few
representative examples of floral mechanisms, but these would be indeed
incomplete without a closing reference to that wonderful tribe of
flowers with which the theory of cross-fertilization will ever be
memorably associated. I have previously alluded to the absolute
dependence of the red clover upon the bumblebee. This instance may be
considered somewhat exceptional, though numerous parallel cases are
known. Among ordinary flowers this intervention of the insect is largely
a _preferable_ intention, and though almost invariably fulfilled, a
large proportion of flowers still retain, as a _dernier ressort_, the
power of at least p