On this afternoon the schoolmaster had a bowl of water and some small green weeds from the nearest pond. He put some of the green plant in a large, clear glass. As it floated, the children coming near to look, one by one saw that the plant seemed supplied with minute green sacs filled with air. “Now, take your seats,” said the master. “This is called a bladder-plant, from these wee, green bladders, whereby it floats. Listen, and Nathan will tell you what he sees. Nathan, come forward.” Nathan came gladly. “Now, tell us what you see in the water, Nathan.” “I see little live things; some have little shells on them like mussels, only they look about as big as tiny pin-heads. Some have little whirling wheels on their heads. A good many are like very, very wee caterpillars.” “Those last are the water-bears,” said the schoolmaster. “Now look at the bladder-plant.” “The bladders,” said Nathan, “are little bags. Their mouths are open. They are set round with hairs. Some of the bags look full of something, and dark. Some of them seem to have some live thing kicking in them. Some are empty, and as you look in at the door it is like a little clear green room. Oh! I see a water-bear swimming up to one! He looks in. He seems to think it is pretty. I guess he wants to know where there is something kicking. He looks in there. Now he goes to an empty one. Now he swims by. No, he changes his mind. He thinks he will go in. He pokes in his head. The little hairs at the door bend inward: they let him go in easy. He is in! Oh! now he is trying to come out!” Great excitement in the listening school—eyes wide open, heads bent forward. “Can he get out?” cried someone. “No! no! he can’t,” exclaimed Nathan, all eager. “The hairs bend in, and let him in, but he cannot get by them to go out! They won’t bend out. Oh, he can’t get out.” The schoolmaster now took one of the dark, full sacs, cut it open with a very fine, sharp instrument, and put it under the glass. “Now what, Nathan?” “Oh, that bag is full of dead things, of what you might call the bones of these bits of creatures, the shells off one of those tiny things like mussels. They are things that have gone in and have got all melted up.” “Here is another,” said the schoolmaster, putting a lighter green sac in place, also cut open. “What now?” “That is the very sac the water-bear looked into to see something kicking. The kicking thing was another water-bear. Now it is dead. The one that went in just now is kicking, too.” The schoolmaster took that sac also, opened it, and released the struggling water-bear. “What now, Nathan?” “He is out, but he doesn’t feel good. He doesn’t swim round as he did before he went in. I think he is going to die, schoolmaster. Oh, here is another bear just going into a sac. Let him out quick, won’t you?” The schoolmaster opened the sac and the freed little animal swam off.