) There is good reason to believe that the
first plants which appeared on this earth were cryptogamic; and judging
from what now occurs, the male fertilising element must either have
possessed the power of spontaneous movement through the water or over
damp surfaces, or have been carried by currents of water to the female
organs. That some of the most ancient plants, such as ferns, possessed
true sexual organs there can hardly be a doubt; and this shows, as
Hildebrand remarks, at how early a period the sexes were separated.
(10/43. 'Die Geschlechter-Vertheilung' 1867 pages 84-90.) As soon as
plants became phanerogamic and grew on the dry ground, if they were ever
to intercross, it would be indispensable that the male fertilising
element should be transported by some means through the air; and the
wind is the simplest means of transport. There must also have been a
period when winged insects did not exist, and plants would not then have
been rendered entomophilous. Even at a somewhat later period the more
specialised orders of the Hymenoptera, Lepidoptera, and Diptera, which
are now chiefly concerned with the transport of pollen, did not exist.
Therefore the earliest terrestrial plants known to us, namely, the
Coniferae and Cycadiae, no doubt were anemophilous, like the existing
species of these same groups. A vestige of this early state of things is
likewise shown by some other groups of plants which are anemophilous, as
these on the whole stand lower in the scale than entomophilous species.
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