Return to Elementary Science I
“I wish,” said Fred, “every fellow in my class had a jolly little sister, like I’ve got, to play schools in the evening. We had a fine lesson on a sponge today. Would you like us to tell you all about it, Norah?”
“That I should,” said his sister.
“Come along then,” said Fred. “I’ve got the sponge ready. I will stand it in a saucer of water, just as teacher did. Now Norah shall take it out of the saucer and put it on the table. What have you done with the water in the saucer, Norah? It is all gone; the saucer is empty. Bring me the sponge. Now squeeze it over the saucer.”
“Oh, I see,” said Norah; “the water all went up into the sponge.”
“Yes, little girl,” said Fred; “and now we will see how it got there. If you look at the sponge, you will find that there are little holes all over it. I will cut a piece of it away, and we shall see that the holes are not on the outside only, but all through the sponge. The sponge is full of holes. Will knows the proper name for these little holes.”
“Oh yes,” said Willie, “teacher told us to call them pores; and as the sponge is full of pores, we say it is porous.”
“Then I suppose,” said Norah, “the sponge sucks up the water because it is porous; the water fills up the holes in it.”
“Right,” said Fred. “Here is a piece of bread. If I stand it in the saucer with only a little water in the bottom, the bread will soon be wet all through.”
“The bread, like the sponge, is porous,” said Norah. “I can see the holes in it.”
The boys came home one day full of delight. Teacher had been giving them a lesson on the dog. As they had a faithful old dog of their own, the lesson pleased them very much.
“Shall we bring Ponto in, and have a chat about him?” said Fred.
Of course, they all said “yes,” and a minute or two later the children were sitting on the floor with Ponto in the middle.
“Now first of all, sister, what does Ponto like best for dinner?” said Fred.
“He likes a piece of meat better than anything,” said Norah.
“Yes,” said Fred, “the dog, like the cat, is a flesh-eater. Open your mouth, Ponto, and let us have a look at your teeth, old boy. Look, Norah, his teeth are sharp and pointed. They are just like pussy’s teeth. They are made for cutting through flesh, not for chewing or grinding. The lower jaw has only one movement—up and down.”
“So far the dog is very like the cat,” said Norah.
“Now let us look a little farther,” said Fred. “Ponto’s head is not like the cat’s head. It is longer and more pointed. If you notice his eyes, you will see that they have no curtain in front, no long narrow slit, like the cat’s eyes. Now let us have a word about his feet. Hold up your paw, Ponto. That’s right, good dog. If we look at all his paws, we shall see that, like the cat, he has five toes on the front and four on the hind ones.”
“Yes,” cried Norah, “and the toes are padded. Does Ponto walk on his toes, too, Fred?”
“Yes, the dog walks on his toes.”
“But,” said his sister again, “I can hear Ponto’s feet on the ground as he runs. I can’t hear pussy’s feet. How is it, if both of them have pads, Fred?”
“Ah,” said Fred, “if you look you will see that Ponto cannot draw back his claws as the cat does. The claws rub the ground at every step, and make a noise. There is just one thing more,” Fred went on. “The dog’s tongue is soft, smooth, and wet, not rough like the cat’s tongue. He does not use it as the cat does. I am going to tell you something very funny though. The dog perspires through his tongue. The sweat never comes out on his skin. When you see Ponto lying down in the sun, with his tongue lolling out, you will know what it means now, Norah.”
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