Page:Popular Science Monthly Volume 12.djvu/218

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206
THE POPULAR SCIENCE MONTHLY.

however, did not keep straight on like the first, but ran a short way, then returned, and then again followed a little farther than the first time. They were evidently scenting the trail of the pioneer, and making it permanently recognizable. These ants followed the exact line taken by the first one, though it was far out of sight. Wherever it had made a slight détour, they did so likewise. I scraped with my knife a small portion of the clay on the trail, and the ants were completely at fault for a time which way to go. Those ascending and those descending stopped at the scraped portion, and made short circuits until they hit the scented trail again, when all their hesitation vanished, and they ran up and down it with the greatest confidence."

That among groups like the Ecitons, in which the sense of sight is imperfect, or even totally wanting, enhanced delicacy of scent and touch must be required in compensation, may be taken as self-evident. With the language of ants, and especially with a possible scent-language, is connected the faculty by means of which denizens of the same city recognize each other under circumstances of great difficulty. In the battles which take place between two nations of the same species, how, save by scent, do the tiny warriors distinguish friend from foe? We are told by some older observers that if an ant is taken from the nest, and restored after the lapse of several months, it is at once received by its companions and caressed, while a stranger ant introduced at the same time is rejected, and generally killed. To a great extent this has been confirmed by recent investigators. The returned exile was not indeed caressed, but was quietly allowed to enter the nest, while a stranger was at once greeted with hostile demonstrations. It has been maintained that this power of recognition is destroyed by water, and that ants will treat a comrade as an enemy if he has received a drenching. This, however, is evidently a mistake. To prevent rain from penetrating into the nests of the agricultural ant, the guards block up the doorways with their bodies, and are often drowned at their posts. But their companions are not thereby prevented from recognizing them, as they try to bring the dead bodies to life.—Quarterly Journal of Science.

 
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HISTORY OF THE DYNAMICAL THEORY OF HEAT.[1]
By PORTER POINIER.
I.

A RECAPITULATION of the various conjectures which have been advanced in explanation of so ever-familiar a sensation as that of warmth or heat, would neither prove particularly feasible nor interesting; for doubtless during the vast period of time which has elapsed

  1. Introduction to an unpublished work on Thermo-Dynamics.