Page:Popular Science Monthly Volume 11.djvu/68

58 had access to many larvæ brought two hundred and fifty-seven friends, while those visiting a glass with few larvæ only brought eighty-two. The result will appear still more striking if we remember that a certain number, say perhaps twenty-five, would have come to the larvæ anyhow, which would make the numbers two hundred and thirty-two as against fifty-seven, a very striking difference.

I have elsewhere discussed the relations of flowers to insects, and especially with bees, and particularly the mode in which the flowers were modified so that the bees might transfer the pollen from one flower to another. Ants are also of considerable importance to plants, especially in keeping down the number of insects which feed on them. So far as I know, however, there are no plants which are specially modified in order to be fertilized by ants; and, indeed, even to those small flowers which any little insect might fertilize, the visits of winged insects are much more advantageous, because, as Mr. Darwin has shown in his excellent work on cross and self fertilization of plants, it is important that the pollen should be brought, not only from a different flower, but also from a different plant, while creeping insects, such as ants, would naturally pass from flower to flower of the same plant.

Under these circumstances it is important to plants that ants should not obtain access to the flowers, for they would otherwise rob them of their honey without conferring on them any compensating advantage. Accordingly, we not only find in flowers various modes of attracting bees, but also of excluding ants; and in this way ants have exercised more influence on the vegetable kingdom than might be supposed. Sometimes, for instance, the flowers are protected by chevaux-de-frise of spines and fine hairs pointing downward (Carlina, Lamium); some have a number of glands secreting a glutinous substance, over which the ants cannot pass (Linnœa, gooseberry); in others the tube of the flower is itself very narrow, or is almost closed either by hairs or by internal ridges, which just leave space for the proboscis of a bee, but no more. Lastly, some, and especially pendulous flowers (Cyclamen, snowdrop), are so smooth and slippery that ants cannot easily enter them, but often slip off in the attempt, and thus are excluded, just as the pendulous nests of the weaver-birds preclude the entrance of snakes. This, however, is a large subject, into which I cannot now enter.

Let me, in conclusion, once more say that, as it seems to me, notwithstanding the labors of those great naturalists to whom I gratefully referred in commencing, there are in natural history few more promising or extensive fields for research than the habits of ants.—Fortnightly Review.