The stickleback gets his name from the fact that some of his fins, one on the back and one on the lower part of the body, have changed to spines or thorns. Different kinds of stickleback have three, four, ten, fifteen, of these thorns. This little fellow is one of the smallest and prettiest of fishes. He is slender, and from one to three inches long. The general length is about an inch and a half. His body is silver below, green and purple in bands on the back, and red and gold on the head and sides. His fins are thin as finest silk. I never saw a prettier little creature. The stickleback is very greedy, very fearless, full of courage, very affectionate, and of all fishes is the most devoted parent. Finally, the stickleback can build a house. The colors of the stickleback brighten or fade according as he feels glad or sad. If he has lost his mate, his home, or his young ones, or if he has been beaten in a fight, he swims off to hide, and his colors grow dull. If he has beaten his enemy, if his children and mate are quite safe in the little house where he has put them, he gleams and glows like a rainbow. Sticklebacks are so fearless that when they are in a pond no noise or shadow will alarm them. You can even catch them without a hook just by dropping among them a string with a worm on it. You may pull up the string with two sticklebacks fast, one on each end of the worm. Little English boys take this way of catching these tiny fish for their globes. When put into a globe or box, they fight sharply at first. They strike each other with their spines, whirl, dart, pretend to be beaten, and then leap back to the fight. They are real little soldiers. Finally, when they have found out which of them all is the strongest, each one chooses his own corner, or shelter by a stone for a home, and defends that against all strangers. The different varieties of sticklebacks build different kinds of houses. One makes a nest like a muff among water-weeds. I will tell you of one kind of nest. The little fish carries straws and bits of grass and moss, and tucks them down into the gravel and sand. He glues them with the glue from his skin. While he is at work he holds and carries his material with his mouth, and presses it into place with his body. Having laid a floor, he builds a little hut of woven fibres and moss. This hut is about as large round as a twenty-five-cent piece. A little door is at the top. He tries the strength of his house by stirring up the water near it with his tail. When all is done Mr. Stickleback swims off to find his mate. He seems to tell her that the house is ready. She is a lazy little creature, and does nothing but frolic in the water. She goes along to the new home, and goes in to lay some eggs there. Mr. Stickleback proudly swims up and down before the home to keep foes away.