How great must be
the advantage obtained by this plant through its exceptional
habit of flowering in the late autumn, and ripening its fruit in
the spring. To anyone who has watched the struggle to approach
the ivy-blossom at a time when nearly all other plants are bare,
it is evident that, as far as transport of pollen and
cross-fertilization go, the plant could not flower at a more
suitable time. The season is so late that most other plants are
out of flower, but yet it is not too late for many insects to be
brought out by each sunny day, and each insect, judging by its
behaviour, must be exceptionally hungry.

"Not only has the ivy the world to itself during its flowering
season, but it delays to ripen its seed till the spring, a time
when most other plants have shed their seed, and most edible
fruits have been picked by the birds. Thus birds wanting fruit in
the spring can obtain little but ivy, and how they appreciate the
ivy berry is evident

[1] For December, 1892, vol. i., p. 730.

107

by the purple stains everywhere visible within a short distance
of the bush."

These remarks suggest that the ivy adopts the converse attitude
towards its visitors to that forced upon the alpine flower. The
ivy bloom is small and inconspicuous, but then it has the season
to itself, and its inconspicuousness is no disadvantage, _i.e._
if one plant was more conspicuous than its neighbours, it would
not have any decided advantage where the pollinating insect is
abundant and otherwise unprovided for. Its dark-green berries in
spring, which I would describe as very inconspicuous, have a
similar advantage in relation to the necessities of bird life.

The experiments of M. C. Flahault must be noticed. This
naturalist grew seeds of coloured flowers which had ripened in
Paris, part in Upsala, and part in Paris; and seed which had
ripened in Upsala, part at Paris, and part at Upsala. The flowers
opening in the more northern city were in most cases the
brighter.[1] If this observation may be considered indisputable,
as appears to be the case, the question arises, Are we to regard
this as a direct effect of the more rigorous climate upon the
development of colouring matter on the blooms opening at Upsala?
If we suppose an affirmative answer, the theory of direct effect
by sun brightness must I think be abandoned. But I venture to
think that the explanation of the Upsala

[1] Quoted by De Varigny, _Experimental Evolution_, p. 56.