I have observed that signs prevail to a great extent among ants. Some years ago I had an opportunity of studying a colony of ants, and I watched them almost daily for several weeks. I had seen it stated that they found their way by the sense of smell, but these observations confirmed my doubts on that point, and I feel justified in saying that they are guided almost, if not entirely, by landmarks. On the bark of a tree from which they were gathering in their winter stores, I observed that there were certain little knots or protuberances by which they directed their course and which they always passed in a certain order. Between these landmarks they did not confine themselves to any exact path, but the concourse would sometimes widen out over the space of more than an inch, but as they approached a landmark every ant fell into line and went in the exact path of the others, which rarely exceeded in any case more than an eighth of an inch in width. Whenever an ant would lose its way it would lift its head high into the air, look around, and then turn almost at right angles from the course it was pursuing towards the path of the others. In scores of cases I observed that the outward-bound ant, when it had been lost and returned to the path, always came on the homeward side of the landmark and passed out. On the other hand, if a homeward-bound ant was lost it would approach from the outward side of the landmark and pass in. About five feet from the ground were two small, round knots, about one-eighth of an inch in height, and a space between them of about the same width. This appeared to be one of their most conspicuous and reliable landmarks, and every ant that I saw pass in or out during the lapse of weeks passed between these two points. The burdened ant always appeared to have the right of way, and when meeting another without a burden there was no question of this right. In such a case the burden was usually held aloft, and the right of way conceded without debate. A little later in the season I had the opportunity of seeing the same colony emigrate to a point about eighty feet distant from their original abode, at which time they carried large burdens and were many days in completing their work, but the same system and methods prevailed. As far as desire can be found in life the means of expression go hand in hand with it, but I do not contend that desire alone is the origin of this faculty. So far as human ears can ascertain, the lowest forms of life appeared to dwell in perpetual silence, but there may be voices yet unheard, more eloquent than we have ever dreamed of. CHAPTER XXV. Facts and Fancies of Speech--Language in the Vegetable Kingdom--Language in the Mineral Kingdom.