书城教材教辅科学读本(英文原版)(套装1-6册)
47723000000188

第188章 第三册(13)

"Pluck one or two of them. You can see that the edges of the barbs are provided with a great number of very small blades-the barbules. Barbule means a little barb.

"These barbules are really little hooks. They interlock themselves one in the other, and so hold the barbs of the web close together.

"Look, while I run my finger along the feather the wrong way. You see the little hooks are pulled apart, and the barbs themselves are separated from each other.

"Teacher showed us that the barbs always point towards the tip of the feather, and away from the quill ; and, in addition to that, every feather on the bird"s body points backwards.

"This is ver y important. As the bird moves through the air the feathers are pressed closer and closer to its body. This helps the bird in its flight, and, at the same time, keeps it warm."SUMMARY

A feather consists of a stem and a web. The stem has a hollow quill, and a shaft ?lled with light pith. The web consists of barbs; the edges of the barbs are held together by the barbules. All the birds" feathers point backwards.

Lesson 05

The Uses of Feathers

"You have not forgotten our chat about feathers, Norah?" said Fred a few evenings later.