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BIG ENCYCLOPEDIA FOR CHILDREN AND ADULTS
Why does nettle sting? Detailed answer
Directory / Big encyclopedia. Questions for quiz and self-education Did you know? Why does nettle sting? There are several varieties of nettle in the world, and not all of them have stinging hairs. Nevertheless, most of us at least once in our lives have been burned by touching this plant. Among those species that sting, the common nettle and Roman nettle are the most common. The latter also burns more painfully than any other. The stinging action of nettles is very similar in mechanism to the action of stinging cells located on the tentacles of sea anemones and jellyfish. Inside these cells are thin, unusually sharp stings, rolled up into rings and straightening at the slightest touch. Nettle stingers develop from a single cell and take the form of hairs, on the sharp ends of which there are small balls that prevent them from damage. If you lightly touch such a ball, it immediately breaks, and a sharp needle digs into the skin. The caustic acid contained inside the sting causes irritation, and sometimes, in especially severe cases, burns on the skin. However, if you gently grasp the stalk of the nettle so that the hairs are pressed against it, then they will not be able to cause you any harm. It should not be thought that nettle is a completely useless plant for humans. In many countries, it is boiled in large cauldrons, providing valuable feed for pigs and poultry. Nettle roots, treated with a solution of alum, are used to obtain yellow dye, and leaves and stems - green. From the fibers of "ramie" (Chinese nettle), with appropriate processing, they produce fabrics, braid, ropes and threads. Author: Likum A.
When did the first theater appear? Theater as we know it originated in Greece as part of a religious ritual. The stage was a circle covered with turf, on which the faithful danced around the altar of Dionysus. The stage was usually located at the foot of the hill so that the audience, who sat on its slopes, could see the dancers. This marked the beginning of the traditional arrangement of Greek theaters - a semicircle of seats located on the slopes of a hill. The word "theatre" is of Greek origin and means "a place for viewing". Theater built in Athens around 500 BC. e., was round and was called parterre. There were performances. Outside the circle, special rooms were built that looked very majestic. This was the prototype of the current scene. These rooms served as a dressing room for the participants in the performance. They were also the screen that became the backdrop for the action of the play. The Greeks made very little use of decorations and did not resort to artificial lighting at all, because the plays were staged during the daytime. In Rome, the first stone theater was built in 52 BC. e. Roman theaters were very similar to Greek ones, but they were built on level ground. The Romans were the first to install seats in the stalls, and the piece was played on a raised stage behind which was a screen. After the Romans converted to Christianity, no theaters were built for thousands of years. The first modern theater was the Farnesi Theater in Parma, Italy. It was built in 1618 or 1619. His stage did not move far into the hall, into the stalls, but was located along one of the walls. A curtain was used to separate the auditorium from the stage, and the change of scenery could be done out of sight of the audience.
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