Certain things in animal life lead me to suspect that animals have some means of communication with one another, especially the gregarious animals, that is quite independent of what we mean by language. It is like an interchange or blending of subconscious states, and may be analogous to telepathy among human beings. Observe what a unit a flock of birds becomes when performing their evolutions in the air. They are not many, but one, turning and flashing in the sun with a unity and a precision that it would be hard to imitate. One may see a flock of shore-birds that behave as one body: now they turn to the sun a sheet of silver; then, as their dark backs are presented to the beholder, they almost disappear against the shore or the clouds. It would seem as if they shared in a communal mind or spirit, and that what one felt they all felt at the same instant. In Florida I many times saw large schools of mullets fretting and breaking the surface of the water with what seemed to be the tips of their tails. A large area would be agitated and rippled by the backs or tails of a host of fishes. Then suddenly, while I looked, there would be one splash and every fish would dive. It was a multitude, again, acting as one body. Hundreds, thousands of tails slapped the water at the same instant and were gone. When the passenger pigeons were numbered by millions, the enormous clans used to migrate from one part of the continent to another. I saw the last flight of them up the Hudson River valley in the spring of 1875. All day they streamed across the sky. One purpose seemed to animate every flock and every bird. It was as if all had orders to move to the same point. The pigeons came only when there was beech-mast in the woods. How did they know we had had a beech-nut year? It is true that a few straggling bands were usually seen some days in advance of the blue myriads: were these the scouts, and did they return with the news of the beech-nuts? If so, how did they communicate the intelligence and set the whole mighty army in motion?