CHAPTER IX.

GENERAL INTELLIGENCE, AND POWER OF FINDING

THEIR WAY.

A NUMBER of interesting anecdotes are on record as to the ingenuity displayed by ants under certain circumstances.

M. Lund, for instance, tells the following story as bearing on the intelligence of ants: '—

'Passant un jour près d'un arbre presque isolé, je fus surpris d'entendre, par un temps calme, des feuilles qui tombaient comme de la pluie. Ce qui augmenta mon étonnement, c'est que les feuilles détachées avaient leur couleur naturelle, et que l'arbre semblait jouir de toute sa vigueur. Je m'approchai pour trouver l'explication de ce phénomène, et je vis qu'à peu près sur chaque pétiole était postée une fourmi qui travaillait de toute sa force; le pétiole était bientôt coupé et la feuille tombait par terre. Une autre scène se passait au pied de l'arbre: la terre était couverte de fourmis occupées à découper les feuilles à mesure qu'elles tombaient, et les morceaux étaient sur le champ transportés dans le nid. En moins d'une heure le grand œuvre

Ann, des Soi. Nat. 1831, p. 112.

s'accomplit sous mes yeux, et l'arbre resta entièrement dépouillé.'

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Bates' gives an apparently similar, but really very different account. The Saüba ants,' he says, 'mount the tree in multitudes, the individuals being all worker-minors. Each one places itself on the surface of a leaf, and cuts with its sharp scissor-like jaws a nearly semicircular incision on the upper side; it then takes the edge between its jaws, and by a sharp jerk detaches the piece. Sometimes they let the leaf drop to the ground, where a little heap accumulates, until carried off by another relay of workers; but, generally, each marches off with the piece it has operated upon.'

Dr. Kerner recounts the following story communicated to him by Dr. Gredler of Botzen :—

'One of his colleagues at Innsbrück, says that gentleman, had for months been in the habit of sprinkling pounded sugar on the sill of his window, for a train of ants, which passed in constant procession from the garden to the window. One day, he took it into his head to put the pounded sugar into a vessel, which he fastened with a string to the transom of the window; and, in order that his long-petted insects might have information of the supply suspended above, a number of the same set of ants were placed with the

sugar in the vessel. These busy creatures forthwith

1 Naturalist on the Amazons, vol. i. p. 26.

• Flowers and their Unbidden Guests, Dr. A. Kerner. Trans. by W. Ogle, 1878, p. 21.

seized on the particles of sugar, and soon discovering the only way open to them, viz. up the string, over the transom and down the window-frame, rejoined their fellows on the sill, whence they could resume the old route down the steep wall into the garden. Before long the route over the new track from the sill to the sugar, by the window-frame, transom, and string was completely established; and so passed a day or two without anything new. Then one morning it was noticed that the ants were stopping at their old place, that is, the window-sill, and getting sugar there. Not a single individual any longer traversed the path that led thence to the sugar above. This was not because the store above had been exhausted; but because some dozen little fellows were working away vigorously and incessantly up aloft in the vessel, dragging the sugar crumbs to its edge, and throwing them down to their comrades below on the sill, a sill which with their limited range of vision they could not possibly see!'

Leuckart also made a similar experiment. Round a ree which was frequented by ants, he spread a band soaked in tobacco water. The ants above the band after awhile let themselves drop to the ground, but the ascending ants were long baffled. At length he saw them coming back, each with a pellet of earth in its mouth, and thus they constructed a road for themselves, over which they streamed up the tree.

Dr. Büchner records the following instance on the authority of a friend (M. Theuerkauf):—

A maple tree standing on the ground of the manufacturer, Vollbaum, of Elbing. (now of Dantzic) swarmed with aphides and ants. In order to check the mischief, the proprietor smeared about a foot width of the ground round the tree with tar. The first ants who wanted to cross naturally stuck fast. But what did the next? They turned back to the tree and carried down aphides, which they stuck down on the tar one after another until they had made a bridge, over which they could cross the tar-ring without danger. The above-named merchant, Vollbaum, is the guarantor of this story, which I received from his own mouth on the very spot whereat it occurred."

In this case I confess I have my doubts as to the interpretation of the fact. Is it not possible that as the ants descended the tree, carrying the aphides, the latter naturally stuck to the tar, and would certainly be left there. In the same way I have seen hundreds of bits of earth deposited on the honey with which I fed my ants.

On one occasion Belt observed 2 a community of leaf-cutting ants (Ecodoma), which was in the process of moving from one nest to another. 'Between the old burrows and the new one was a steep slope. Intead of descending this with their burdens, they cast

Mind in Animals, by Prof. Ludwig Büchner, p. 120. • Naturalist in Nicaragua, O. Belt, p. 76.

them down on the top of the slope, whence they rolled to the bottom, where another relay of labourers picked them up and carried them to the new burrow. It was arousing to watch the ants hurrying out with bundles of food, dropping them over the slope, and rushing back immediately for more.'

With reference to these interesting statements, I tried the following experiment:

October 15 (see Fig. 10).-At a distance of 10 inches from the door of a nest of Lasius niger I fixed Fig 10. an upright ash wand 3 feet 6 inches high (a), and from the top of it I suspended a second, rather shorter wand (b). To the lower end of this ✔ second wand, which hung just over the • entrance to the nest (c), I fastened a flat glass cell (d) in which I placed a number of larvæ, and to them I put three or four specimens of L. niger. The drop from the glass cell to the upper part of the frame was only an inch; still, though the ants reached over and showed a great anxiety to take this short cut home, they none of them faced the leap, but all went round by the sticks, a distance of nearly 7 feet. AS P.M. there were over 550 larvæ in the glass cell, and I reduced its distance from the upper surface of the nest to about of an inch, so that the ants could even touch the glass with their antennæ, but could not reach up nor step down. Still, though the drop was so small, they all went round. At 11 P.M. the