书城教材教辅科学读本(英文原版)(套装1-6册)
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第282章 第三册(107)

"Teacher has been showing us today," said Fred, "how well the fish is fitted in every way for its life in the water. He showed us the herring again, and made us notice how the very shape of its body helps its movements. It is big in the middle and tapers to a sharp point both ways. It is just the shape to enable it to cleave its way through the water with the greatest ease.""I remember the bird"s body is built on much the same plan," said Norah, "and for the same purpose." "He next showed us the backbone of a herring, and broke the little bones in it apart to let us seehow they are joined to each other. Each little bone has a hollow socket on both sides, and they are joined by the rim of one socket fitting closely to therim of the next, so as to form a hollow ball between the two. "I"ve got a backbone like it here.

Look at it while I separate the bones, and you will understand it all. It is quite different from the backbone of the snake, the bird, or the rabbit.

It makes the body of the fish very