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102 ON THE SEXUAL OEGANS OF THE CYCADACE^.
When we examine the relations of the sexual organs in plants, it
seems in many cases that the function of fertilization has been rendered
in some manner difficult or even impossible. It might be said that
nature does not wish to see its end attained except circuitously ; as far
as Angiosperms are concerned, a more precise knowledge of insect-
agency has already to a considerable extent penetrated the mystery.
But there are other sreat divisions of the vegetable kingdom in
which this agency has no place, and it is these which were already in
existence before hausteUate insects. I regard as such all the Crypto-
gams ; among these the spermatozoids move towards the female
organ by means of humid surfiices, drops of water, etc. Among the
dicEcious and monoecious Phanerogams which have preceded herma-
phrodite species on the surface of the globe, their pollen is carried
in excessive abundance by the winds, and the chances are greatly in
favour of one of the millions of grains arriving at its destination.
As to Cycads, I do not at present know any property which would
be of a nature to attract insects in particular towards their female
cones, either from nectar in the flowers, colour, or odour; at the same
time, when one takes into consideration their being dioecious, and the
complete occlusion of their female cones (except in the Cycads, where
the ovvdes have the exostorae outside, which would allow access to the
pollen-grain), it becomes almost impossible to comprehend how the
for example, our most conspicuous species or trees hold, for tlie most part, a
lower position than a large proportion of our herbaceous plants, whose perisliable
tissues would leave no trace in deposits, which might, however, contain
fruits and leaves of CinpidifercE in abundance. Without a knowledge to the
contrary, these miglit lead an observer in examining such a de])osit to the conclusion
that the Cupuliferce almost wholly composed our vegetation. Even
without this consideration, it will hai'dly be admitted that Angiosperms had at
tlieir first appearance the same preponderance that they now possess. In America
plants so modern in character, as to be at first believed to be of Tertiary
age, have been found in Cretac-eous rocks of even a lower horizon. ('Journal
of Jiotany,' pp. 82-83, ISGO.),
Tiie .connection between the periods of appearance in time of Angiosperms
and haustellate insects is undoubtedly interesting. It must, however, be remembered
that it rests on negative evidence, wliich in geology is necessarily far
from conclusive. Their interdependence may be tlie cause of our finding them
associated in time, but not necessarily so, as one of them may have preceded
the other, witliout our having at present evidence of the fact. Theories as to
evolution should only bo sparingly illustrated from geological phenomena, and
can draw but little support from them. For example, Dr. Debey has obtained
about ten s])ecies of insects from the Aix-la-Chapelle beds. Yet these belong
to the families CureulionldcB or CarabidcB, which are mandibulate insects.
—W. T. D.