Why do carnations sleep after coming into the city?

In 1908, a flower grower from Chicago in the United States went to consult a botanist. He said: "I have many beautiful carnations in the countryside, and they bloom very brightly there, but when they reach the city, they come down with sleeping sickness." The botanist thought it might be because the composition of the air in the city differed somewhat from that in the countryside. To confirm his idea, he took all kinds of gases and put them inside a glass cover, then placed blooming carnations inside, and the result showed that as long as the cover contained a few parts per million of ethylene gas, the blooming carnations would wither. It turned out that in the ship transporting the carnations, some lighting gas had leaked out. At the time, after another physiologist learned of this matter, he placed a frog in a glass bottle and slowly added ethylene for an experiment. When the ethylene had been added until it filled four-fifths of the bottle, the frog finally lay on the ground motionless and asleep, but when the frog was taken out, after a few minutes it revived again. He then conducted countless experiments with various animals, and ethylene could make them all sleep temporarily. From then on, ethylene became an anesthetic used by surgeons during operations to reduce patients' pain.