"Nurth, do turtle-doves live in the mud?" said Pip. "Nonsense," said Bob, "as if birds ever lived in the mud!" "Well," said Pip, "thum thwallows, I _know_, make their neths of mud, and then they live in their neths, and that's living in mud. But here comth the Profethor; let's see what heeth found. It's thumthin in a glath." The Professor came up, walking very slowly across the grass; then stepped carefully up upon the piazza, and, as he passed the window, he called for some one to come and open the front door. All the children ran together, and opened the door with such a flourish, the Professor was obliged to call out, "Stand off! Hands off!" "Will it splode?" said Pip. "Will it bite?" said Bob. "Will it fly away?" said Tom. "It will splode," said the Professor, "and it will fly away; but it won't bite." "Oh my!" said Pip, "what can it be? I never heard of any creature splodin!" The Professor looked pleased; his face was red, his hair was tumbled, his coat was torn, and his boots and trousers were muddy. "You look as if you had had a hard time catching the creature, whatever it is," said nurse. "You'd better leave it out-of-doors now, and clean yourself, and come and eat your luncheon." "Oh, please, nurse, let's see it now!" said all the children; and nurse, who wanted to see it herself, agreed. "You can't see it," said the Professor; "it's invisible! You can't see it till it disappears!" "Oh dear," said Pip, "I just ache to know about it." "Well," said the Professor, "light mamma's wax-taper." "I don't see what good lighting a taper will do, if the creature's invisible," said Bob. The Professor set his burden down on the table. It was a saucer filled with water, and in the water stood a tumbler upside down. There was nothing to be seen in the tumbler. The Professor struck an attitude. "What I have in this tumbler, nurse and children, was obtained with great difficulty. I've been about it ever since lesson-time." "Where did you find it?" says Pip. "How came you to know about it?" says Tom. "I should think it would be hard to catch nothing," says Bob. "I found it in the water, in the little pool in our woods. I saw it first the other night in the dark, and I caught it to-day when it was hiding. I took a long stick and gently stirred up the dead leaves that lie rotting on the bottom, and he began to come up--first one, then another--now here, and now there." "Ho! ho!" says Bob. "How could that be? How could _he_ come up in pieces, and in different places?" "Poor thing!" said Pip. "He wath dead!" "Oh, if he's dead I don't care about him," says Bob. "He's far from dead," said the Professor; "and though he was in pieces, he's all together now, and safe in this tumbler." And then, seizing the lighted taper, he turned up the tumbler, held the taper quickly to its mouth, and--Pop! went something, with a quick flash. "Oh, fire-works!" says Bob.