the reproductive act. The stigma is observed to become moistened, and
even to become distinctly odorous. Often, too, it becomes intensely
congested with the juices of the plant, and sometimes even acquires
an uncommon and most remarkable degree of contractility. This is the
case with the stigma of the tulip and one variety of sensitive plant,
and is in these plants observed to occur not only after the application
of the pollen to the stigma, but when excited by any other means of
stimulation. The flowers of some plants, during and after fecundation,
also show an increase of heat, in some cases so marked as to be readily
detected with the thermometer. This is said to be the case with the
_arum_ of Italy.

In some plants in which the pistil is longer than the stamens, thus
elevating the stigma above the anthers, the female organ is often
observed to bend over and depress itself so as to come within reach
of the anthers.

In most instances the fecundation of flowers is chiefly effected
through a purely mechanical process, though in these cases also we see
a wonderful adaptation of parts to conditions.

When the male and female parts of flowers are situated on different
plants, as is the case in the willow, the poplar, the melon vine, and
many other species, the pollen of the male flower is wafted by the wind
or gentle breeze to the stigma of the female flower, which will usually
be found at no very great distance, although fertilization may take
place in this way at very considerable distances. Bees, moths, and many
other species of insects, serve a very important purpose in this work,
transporting the fertilizing dust upon their wings, antennae,
sucking-tubes, and feet. Small birds, and even the humble snail, which
would scarcely be credited with any useful function, are also very
serviceable in the same direction. The part performed by insects in
the reproductive process of many plants is so great that they have been
very poetically termed "the marriage priests of flowers."

Nature provides for thorough fecundation in these cases by placing the
plants which bear the male and the female flowers near each other. This
fact accounts for the unproductiveness of certain varieties of
strawberries unless mixed with plants of some other variety, it being
well known to nursery-men that some varieties produce only the female
parts of flowers.

Modes of Fecundation in Animals.--The modes by which fecundation is
effected in ani