협동

과학동아 1992년 05호

batch. When the normal sperm is on its way to successful impregnation, the deformed sperm clump together to form a plug that prevents other sperm from entering the reproductive tract.Certain bacteria apparently cooperate to hunt and attack prey. Other bacteria, very long ago, entered living cells not to destroy them, but to cooperate for mutual benefit. These bacteria became the mitochondria, ...

화산

과학동아 1991년 09호

into steam by the internal heat of the planet. The steam builds up, the pressure increases, and eventually, the plug blows out.Usually, the blowout is moderate and the result is a more or less gentle volcanic action. Sometimes however, the blowout is enormous and many thousands of people are killed.In Japan the Mt. Fugen volcano in the Unzen Mountains was widely considered to be dead. It had ...