He never seemed to stir from his majestic calm. He stole across the line of vision, but without visible effort. He crossed the path of other fish. He sailed above them or below them; but he seemed to feel himself all alone, and to notice nothing. A fisher who had watched pike told me that, when he watched one lying in a pool, he was sure that the fish saw him. It did not seem to make any motion. But the fish changed its place. Soon it was gone. In the next tank to the one I spoke of, were flounders. They swam with a wave-like motion of the whole body. They did not swim straight forward. They went up and down in curves. Their motion was much like the flight of short-winged, heavy birds. In fact, a sole which had its eyes and mouth set upon a kind of skull-shaped head, on the upper side of the flat body, looked much like a dim, first idea of a bird. The fish in the tank were not fish that fed on each other, and they never seemed to notice each other at all. I saw some kinds of fish asleep. A dog-fish lay asleep on the sand, with his nose in a corner, for half a day. He looked as if he were dead. Three hermit crabs[32] were crawling about over him. He never stirred. He did not seem to notice their sharp claws and their jostling shells. This sleeping of the dog-fish reminded me of what I had seen in pools where fish lie basking in the sunshine. Some fish are very fond of lying in a sunny spot. Others will get into a shadow, and lie there with great content. I found in my study of fish life in tanks, that fish are given to fighting. Some of them fight with their nearest relatives. In a small tank I saw two fish that fought and bit each other so cruelly that they had to be parted. There had been several fish in this tank, and all but two had been killed in their battles. Then a glass partition had been put in the middle of the tank, and one fish lived on each side. They swam up to this clear wall, laid their noses against it, and glared at each other. Another fact I remarked in fish is the clearness and keenness of their vision, and the quick way in which they will dart at food. When they see something that they wish to eat dropping down through the water, they spring at it with open mouths, and seem never to miss their mark. When they need more air than they can get from the water, they swim to the surface and take a gulp of air and water. When they are sick, they do not swim, but lie on their sides, as if they feel too weak to make any effort. When they are dead, the bodies turn over and float on their backs. It is said that fish can reproduce parts that they have lost, as crabs and star-fish can. At least, they can easily live when an eye or part of their mouth or a fin is gone. They seem to suffer little from such a loss. A fish that has a wound, or has just lost an eye, will swim about and eat as if it felt no pain.