  Uncle George’s tank was very simple. It was made up of several large glass bells, such as the gardener uses for covering tender plants. Uncle George’s Aquarium. Each glass bell had a nob on the end of it. Uncle George got a large block of wood for each bell-jar. This block he hollowed out with a chisel. He next bored a large hole in the centre of the hollow to hold the nob. Then he cut a piece of thick green cloth into a round shape, with a hole in its centre. This piece of cloth was placed over the hollowed out part of the block, and the bell-jar, turned upside down, was placed in the block so that the glass nob fitted into the hole. Uncle George fitted up four of these tanks and filled them with fresh water. The frog spawn was put into the first vessel. The next was for the newts. The third one held the caddis worms and some other curious creatures that had been found in the ditch. In the fourth vessel were half a dozen pretty little fishes called stickle-backs, which the boys had caught in the brook. Some water weeds and a few water snails or whelks were put into each vessel, except that with the frog spawn in it. Every other morning Uncle George changed the water by means of a tube which he called a siphon. This was a piece of lead pipe, about two feet long, and bent in the middle into the form of the letter U. “The water weeds are very pretty,” said Frank. “They are,” replied his uncle, “and they are also very useful. They help to keep the water pure. I should have to change the water every day if there were no weeds in it. Stickle-backs, Pond Weed, etc., in Aquarium. “The whelks also are most useful. They are the road-men of our ponds and streams. They eat up all It was great fun feeding those little fishes. They were fed sometimes on raw meat chopped very fine, sometimes on little pieces of biscuit. At first they were very shy, but they soon got over that. In less than a week they were quite at home, and would come up to the top of the water and take tiny pieces of beef from the boys’ fingers. They would swim after Frank’s finger as he drew it round the tank, and would even leap out of the water for food that was held out to them. At times they darted about as if playing “hide and seek” among the water weeds. By and by the boys noticed that every time one of the little fish darted at another, the three cruel spines rose up on his back, and that he was really trying to spear his neighbour. One morning a dead stickle-back was found in the bottom of the tank. A few days later another little fish was picked out pale and stiff. “They are killing one another,” said Frank. “What shall we do?” “If any more of this fighting goes on we shall have to put them back into the brook,” said Uncle George. “Do they always fight?” “No, not always—only in spring-time when they are mating. Look! there is one of them getting very pretty. He is the victor—the bully of the pool.” “Let us call him Bully,” said Dolly; “he is bigger than the others, and oh, so much more beautiful.” Next day another stickle-back was found dead, and Bully’s colours were much brighter. He darted about as if the whole tank belonged to him. He was really a lovely fish now, and he seemed to know it by the proud way in which he dashed about, showing off his fine slender body all shiny with crimson, blue, and gold. He was, as Dolly said, “Just like a little bit of rainbow.” But before the evening a very curious thing took place. Bully seemed to have suddenly lost all his fine colours; and instead of swimming proudly at the top of the tank, he slunk sulky to the bottom. The strange thing was that another stickle-back—a smaller fish than Bully—was now brightly coloured, and seemed to be lord of the tank. “Bully has been beaten,” said Uncle George, “and his victor has taken not only the courage but the colour out of him.” “It serves him right, I think, for being so proud and so cruel. But what is the meaning of all this fighting and change of colours, Uncle George?” “Oh, it is very simple, Frank. There is a lady stickle-back in the question; and, like the brave knights of old, our little stickle-backs are trying to win her by fighting. “The victor will marry her. They will build a neat little nest for themselves, and live happily together. “To-morrow we will take them back to the brook, where the weak ones will be better able to escape. “In June we will visit the brook. If we are lucky “When the family are hatching out, the plucky little stickle-back bravely defends the nest. “He drives away water-beetles, perch, and other fishes much larger than himself. For well he knows that these visitors would quickly gobble up his darlings if they got the chance.” Stickle-backs and Nest. Exercises on Lesson VIII.
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