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Page:Popular Science Monthly Volume 19.djvu/514

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THE POPULAR SCIENCE MONTHLY.
To turn back these stragglers and keep them out of sight for a number of days, sometimes for a fortnight, it is sufficient to kill one or two ants on the trail. . . . The moment the spot is reached an ant turns abruptly and makes for home, and in a little while there is not an ant visible on the wall.

Many other cases might be quoted to show that ants are able to communicate information to one another; but, to save space, I shall pass on to Sir John Lubbock's direct experiments upon this subject. Three similar and parallel tapes were stretched from an ant's nest to three similar glass vessels. In one of the latter Sir John placed several hundred larvæ, in another only two or three larvæ, and the third he left empty. The object of the empty glass was to see whether any ants might not run along the tapes without any special reference to the obtaining of larvæ; and this was found not to be the case. Sir John then put an ant to each of the other two glasses; they each took a larva, carried it to the nest, returned for another, and so on. Each time a larva was taken out of the glass containing only two or three, Sir John replaced it with another, so that the supply should not become exhausted. Lastly, every ant (except the two which had first been put to the larvæ), before reaching home with her burden, was caught and imprisoned till the observation terminated.

The result was, that during forty-seven and a half hours the ants which had access to the glass containing numerous larvæ brought 257 friends to their assistance; while during an interval of five and a half hours longer those which visited the glass with only two or three larvae brought only 82 friends. This result appears very conclusive as proving some power of definite communication, not only as to where food is to be found, but also as to the road which leads to the largest store. Further experiments, however, proved that these ants are not able to describe the precise locality where treasure is to be found. For, having exposed larvæ as before and placed an ant upon them, he watched every time that she came out of the nest with friends to assist her; but, instead of allowing her to pilot the way, he took her up and carried her to the larvæ, allowing her to return with a larva upon her own feet. Under these circumstances the friends, although evidently coming out with the intention of finding some treasure, were never able to find it, but wandered about in various directions for a while, and then returned to the nest. Thus, during two hours, she brought out altogether in her successive journeys no less than 120 ants, of which number only five in their unguided wanderings happened by chance to find the sought-for treasure.

Memory.—The general fact that, whenever an ant finds her way to a store of food or larvæ, she will return to it again and again in a more or less direct line from her nest, constitutes ample proof that the ant remembers her way to the store of food. It is of interest to note that the nature of this insect-memory appears to be identical with that of memory in general. Thus, a new fact becomes impressed upon ant-