HOURS LIVING NATURE.
Have you heard anything about the "flower" watch? They look very impressive - the flowers open petals of a different,   but for each fixed time of day. For example, at 5 o'clock in the morning blooming buds of wild rose and poppy, in 10 hours - mother and stepmother to 8 hours in the air in the evening there is a subtle and delicate scent of sweet tobacco, and after another hour of 'start smelling wild orchid.
How did the flowers know the exact time of day?
Originally, scientists thought that the reason for this (the ability of plants is their ability to monitor the position of the sun. But not only the plants have a sense of time, even more so they have pets. In 1729 Mr. astronomer de Meran found that the diurnal movement of leaves of plants kept in total darkness. Then there was another hypothesis - maybe the plants and animals feel the Earth's rotation?
In order to prevent rotation of the Earth, the scientists decided to conduct an experiment at the South Pole. Carefully shaded cockpit with animals and plants (placed on a platform whose rotation in one case, the offset rotation of the earth, and in another it accelerated and slowed in the third. The experiments lasted for more than two months. As a result, it was shown that in plants and animals preserved in all cases, the frequency of behavior, which is close to the daily.
This periodicity in the behavior of living organisms, called the circadian rhythm (from the Latin word «circa» - and about «dies» - day).