x
structure, and, as each separate part is liable to inherited variations, I
conclude that each feather certainly generates a large number of gemmules;
but it is possible that these may be aggregated into a compound gemmule.
The same remark applies to the petals of a flower, which in some cases are
highly complex, with each ridge and hollow contrived for special purposes,
so that each part must have been separately modified, and the modifications
transmitted; consequently, separate gemmules, according to our hypothesis,
{383} must have been thrown off from each cell or part. But, as we
sometimes see half an anther or a small portion of a filament becoming
petaliform, or parts or mere stripes of the calyx assuming the colour and
texture of the corolla, it is probable that with petals the gemmules of
each cell are not aggregated together into a compound gemmule, but are
freely and separately diffused.

* * * * *

Having now endeavoured to show that the several foregoing assumptions are
to a certain extent supported by analogous facts, and having discussed some
of the most doubtful points, we will consider how far the hypothesis brings
under a single point of view the various cases enumerated in the First
Part. All the forms of reproduction graduate into each other and agree in
their product; for it is impossible to distinguish between organisms
produced from buds, from self-division, or from fertilised germs; such
organisms are liable to variations of the same nature and to reversion of
character; and as we now see that all the forms of reproduction depend on
the aggregation of gemmules derived from the whole body, we can understand
this general agreement. It is satisfactory to find that sexual and asexual
generation, by both of which widely different processes the same living
creature is habitually produced, are fundamentally the same.
Parthenogenesis is no longer wonderful; in fact, the wonder is that it
should not oftener occur. We see that the reproductive organs do not
actually create the sexual elements; they merely determine or permit the
aggregation of the gemmules in a special manner. These organs, together
with their accessory parts, have, however, high functions to perform; they
give to both elements a special affinity for each other, independently of
the contents of the male and female cells, as is shown in the case of
plants by the mutual reaction of the stigma and pollen-grains