英文科學(xué)讀本 第三冊(cè)·Lesson 25 The Frog

Lesson 25 The Frog

Come and see what we've got, Norah, said Fred.

Oh, you dreadful boys, said Norah. "It's a nasty, ugly frog. I don't like frogs."

But we had a fine lesson about the frog, Norah, said Will. "He's a poor, harmless, little creature, and I am sure you would like to know something about him, although I am bound to say he is not very handsome. See what you can find to tell her about him, Fred; and here, I've got your picture book all ready."

Well, just look at him as he sits there, said Fred. "His great, broad head, wide mouth, and goggle eyes seem exactly suited to his broad, squat, ungainly body, and I must say Norah is right. He certainly is ugly. At least I can't call him good-looking."

Then, too, compare his long hind legs with his little, short forelegs. They look awkward as he sits there, but see, when I put him on the ground, what good use he makes of those strong, hind legs in leaping.

Norah gave a little scream as the frog leaped towards her, but the boys soon had him again safe enough.

Look at his feet, Norah, said Fred. "The hind feet have five toes and are webbed. What does this tell us?"

The animal is made to swim, said Norah. "I have often watched the frogs swimming; they seem quite at home in the water."

Poor little thing, she added, "he sits quiet enough," and then she thought she would venture to stroke him. But Mr. Frog was not used to these little attentions, and he leaped away.

She gave a shudder as her hand touched his cold, clammy body. In fact she had hardly got over her fright when Fred came back again with him in his hand. He told her that the frog's skin is always cold, and covered with a slimy fluid.

If a frog were put into a dry place, the skin would quickly shrink and become stiff, and the animal would die. The skin is very porous, and absorbs water like a sponge.

Now, he added, "I think I had better tell you about the frog and his food. If we could see inside his mouth, we should find that the upper jaw contains a row of sharp pointed teeth, and there are no teeth in the lower jaw."

But the tongue is more wonderful than the teeth. Instead of springing from the back of the mouth, as the tongues of most animals do, his tongue has its root in front, and points backward towards the throat. He can when he wishes throw the tongue forward a long way beyond the mouth.

He preys on living insects—slugs, grubs, worms, and snails. He swallows his prey whole. The sharp teeth in the upper jaw are to help him to hold his slippery prey, while he swallows them. They are not meant for chewing or tearing.

But his great tongue is his fly-trap. It is always covered with a thick, slimy fluid. As sure as a fly comes within reach, the slimy tongue darts forward like lightning, and never misses its prey.

SUMMARY

The frog can live in the water as well as on the land. His hind feet are webbed for swimming. His body is always cold. He has teeth in the upper jaw only. The root of his tongue is in front; he can throw it forward a long way, to catch the insects and grubs, which are his food.