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Sir John Lubbock, indeed, even suggests–and how the suggestion would have charmed ‘Civilisation’ Buckle!–that to this difference of food and habit the distinctive colours of the various species may very probably be due. The ground which he adduces for this ingenious idea is a capital example of the excellent use to which out-of-the-way evidence may be cleverly put by a competent evolutionary thinker. ‘The Baltic amber,’ he says, ‘contains among the remains of many other insects a species of ant intermediate between our small brown garden-ants and the little yellow meadow-ants. This is possibly the stock from which these and other allied species are descended. One is tempted to suggest that the brown species which live so much in the open air, and climb up trees and bushes, have retained and even deepened their dark colour; while others, such as the yellow meadow-ant, which lives almost entirely below ground, have become much paler.’ He might have added, as confirmatory evidence, the fact that the perfect winged males and females of the yellow species, which fly about freely during the brief honeymoon in the open air, are even darker in hue than the brown garden-ant. But how the light colour of the neuter workers gets transmitted through these dusky parents from one generation to another is part of that most insoluble crux of all evolutionary reasoning–the transmission of special qualities to neuters by parents who have never possessed them.

This last-mentioned yellow meadow-ant has carried the system of domestication further in all probability than any other species among its congeners. Not only do the yellow ants collect the root-feeding aphides in their own nests, and tend them as carefully as their own young, but they also gather and guard the eggs of the aphides, which, till they come to maturity, are of course quite useless. Sir John Lubbock found that his yellow ants carried the winter eggs of a species of aphis into their nest, and there took great care of them. In the spring, the eggs hatched out; and the ants actually carried the young aphides out of the nest again, and placed them on the leaves of a daisy growing in the immediate neighbourhood. They then built up a wall of earth over and round them. The aphides went on in their usual lazy fashion throughout the summer, and in October they laid another lot of eggs, precisely like those of the preceding autumn. This case, as the practised observer himself remarks, is an instance of prudence unexampled, perhaps, in the animal kingdom, outside man. ‘The eggs are laid early in October on the food-plant of the insect. They are of no direct use to the ants; yet they are not left where they are laid, exposed to the severity of the weather and to innumerable dangers, but brought into their nests by the ants, and tended by them with the utmost care through the long winter months until the following March, when the young ones are brought out again and placed on the young shoots of the daisy.’ Mr. White of Stonehouse has also noted an exactly similar instance of formican providence.

The connection between so many ants and so many species of the aphides being so close and intimate, it does not seem extravagant to suppose that the honey-tubes in their existing advanced form at least may be due to the deliberate selective action of these tiny insect-breeders. Indeed, when we consider that there are certain species of beetles which have never been found anywhere except in ants’ nests, it appears highly probable that these domesticated forms have been produced by the ants themselves, exactly as the dog, the sheep, and the cow, in their existing types, have been produced by deliberate human selection. If this be so, then there is nothing very out-of-the-way in the idea that the ants have also produced the honey-tubes of aphides by their long selective action. It must be remembered that ants, in point of antiquity, date back, under one form or another, no doubt to a very remote period of geological time. Their immense variety of genera and species (over a thousand distinct kinds are known) show them to be a very ancient family, or else they would not have had time to be specially modified in such a wonderful multiformity of ways. Even as long ago as the time when the tertiary deposits of Oeningen and Radoboj were laid down, Dr. Heer of Zurich has shown that at least eighty-three distinct species of ants already existed; and the number that have left no trace behind is most probably far greater. Some of the beetles and woodlice which ants domesticate in their nests have been kept underground so long that they have become quite blind–that is to say, have ceased altogether to produce eyes, which would be of no use to them in their subterranean galleries; and one such blind beetle, known as Claviger, has even lost the power of feeding itself, and has to be fed by its masters from their own mandibles. Dr. Taschenberg enumerates 300 species of true ants’-nest insects, mostly beetles, in Germany alone; and M. Andre gives a list of 584 kinds, habitually found in association with ants in one country or another. Compared with these singular results of formican selection, the mere production or further development of the honey-tubes appears to be a very small matter.