Consider Her Ways by Frederick Philip Grove

The most interesting, not to say alarming feature of this adventure consisted in the proof which it afforded of the fact that there were Ecitons about. It was, of course, one of our tasks to secure what information we could bearing on the life, the habits, and the anatomy of these ants. But, seeing that their observation was fraught with considerable danger, I had made up my mind to leave it over to the end. We could not afford to run the risk of being greatly reduced in number right from the start; and that was the reason why we had so far travelled by night. For Ecitons, though almost blind, hunt in daytime. In view of their at least partial blindness, this could not be explained by conditions of light. In fact, there is one race of Ecitons which is absolutely blind (Eciton Cecum); and these hunt with the same efficiency, if not a greater one as those endowed with a vestige of sight, and, what is more important, also in daytime. They are almost completely hypogeic; and when they have to cross open rocky stretches where not even a cover of dead leaves is available, they construct superterranean galleries, using a sort of masonry in the construction of which they are highly adept. Since this race of the blind Ecitons is the one which is geographically most widely distributed, it can readily be inferred, as Bissa-tee pointed out, that the whole trend of evolution, within that genus, must be in the direction of blindness: for some reason or other blindness favours, instead of handicapping, them in the struggle for existence. The fact, then, that Ecitons hunt in daytime must be explained by conditions of temperature rather; and this led me to a further conjecture. Our geographers had already reported that, though our progress in a south-north direction had so far been small, the whole trend of the Narrows being westward, there had already been a slight lowering of the mean temperature, perceptible only to trained observers and by the most delicate physiological tests. The spread between the temperatures at noon and midnight had also increased. This led me to think that, since sooner or later our route would bend more and more to the north, this lowering of the mean temperature would become more and more pronounced. If, then, the difference between day and night was even here sufficient to force the Ecitons to go into bivouac at night, it seemed highly probable that, as we proceeded north, the limit of their distribution would be reached as soon as the daytime temperature fell to a low enough level, at least occasionally, to prevent their being abroad: from then on only did I think it safe to travel during the day.

When, therefore, our work at this station was finished and we all had sufficiently recovered from the effects of fatigue and hunger, I set the hour of departure once more for sunset. To omit all detail, we thus marched for another 27 nights. Many minor observations were made by geographers, zoologists, botanists and meteorologists; and these were reported every morning before we went into our cluster camp. When they were of special interest or too long to be committed to memory, Adver-tee was employed to record them on trees marked in some conspicuous way, so that we could pick them up again on our way home. I often admired the skill with which Adver-tee could compress a great deal of meaning into very brief scents.