书城教材教辅科学读本(英文原版)(套装1-6册)
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第269章 第三册(94)

""I never felt so savage before, but I"ve made many a good meal since then on grubs, insects, worms, and slugs.

""As I grew larger and larger my skin from time to time split, and I always tore it off with my paws, and swallowed it every bit. There was each time a new one underneath to fit me.""SUMMARY

The frog comes from an egg laid by its parent at the bottom of the water. The egg rises to the surface, and is hatched by the heat of the sun. It begins life as a tadpole, with no limbs; it breathes by means of gills, like a ?sh, and feeds upon the green shoots of the water-plants. It passes through various stages, and undergoes many changes for about six or eight weeks. At the end of that time it leaves the water as a fully-developed frog, with lungs, not gills; with four limbs, but no tail; and with even its feeding instincts changed. The frog feeds upon worms, grubs, and insects.

Lesson 32

Coal-Gas

"We have been learning more about coal-gas to- day, Norah," said Willie. "Let us call Fred in and have a chat about it."Fred came in, and began by asking Norah to tell all she could remember about this gas.