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Page:Popular Science Monthly Volume 19.djvu/511

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INTELLIGENCE OF ANTS.

INTELLIGENCE OF ANTS.
By GEORGE J. ROMANES.

I HAVE frequently been much struck by the absence of information, even among professed naturalists and professed psychologists, concerning the intelligence of ants. The literature on the subject being scattered and diffused, it is not many persons who have either the leisure or the inclination to search it out for themselves. Most of us, therefore, either rest in a general hazy belief that ants are wonderfully intelligent animals, without knowing exactly in what ways and degrees the intelligent action of these animals is displayed; or else, having read Sir John Lubbock's investigations, we come to the general conclusion that ants are not really such very intelligent animals, after all, but, as was to have been expected from their small size and low position in the zoölogical scale, it only required some such methodical course of scientific investigation to show that previous ideas upon the subject were exaggerated, and that, when properly tested, ants are found to be rather stupid than otherwise. I have therefore thought it well to write a paper for this widely circulated review, in order to diffuse some precise information concerning the facts of this interesting branch of natural history.

Not having any observations of my own to communicate, I have no special right to be heard on this subject; but, as I have recently had occasion to read through the literature connected with it, I am able to render what I may call a filtered abstract of all the facts which have hitherto been observed by others. It is needful, however, to add that the filter has been necessarily a close one; if I had a large volume instead of a short paper as my containing vessel, the filtrate would still require to be a strongly condensed substance.

Powers of Special Sense.—Let us take first the sense of sight. Sir John Lubbock made a number of experiments on the influence of light colored by passing through various tints of stained glass, with the following results: 1. The ants which he observed greatly disliked the presence of light within their nests," hurrying about in search of the darkest corners "when light was admitted. 2. Some colors were much more distasteful to them than others; for while under a slip of red glass there were on one occasion congregated 890 ants, under a green slip there were 544, under a yellow 495, and under a violet only 5. 3. The rays thus act on these ants in a graduated series, which corresponds with the order of their influence on a photographic plate. Experiments were therefore made to test the effect of the rays on either side of the visible spectrum, but with negative results. In considering these experiments, however, it is important to remember that other observers (especially Moggridge in Europe, and McCook in America) have