“Late Flowering Plants.—­While we write, the ivy is in flower, and bees, wasps, and flies are jostling each other and struggling to find standing-room on the sweet-smelling plant.  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.

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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.

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experiment is not to be found in direct climatic influence upon the colour, but in causes which lie deeper, and involve some factors deducible from biological theory.

The organism, as a result of the great facts of heredity and of the survival of the fittest, is necessarily a system which gathers experience with successive generations; and the principal lesson ever being impressed upon it by external events is economy.  Its success depends upon the use it makes of its opportunities for the reception of energy and the economy attained in disposing of what is gained.