Page:Researches on Irritability of Plants.djvu/113

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RESEARCHES ON IRRITABILITY OF PLANTS

ozone, was showing signs of fatigue, as evidenced by the gradual diminution of the heights of successive responses.


Fig. 46.—Stimulating action of ozone.


Fig. 47.—Effect of carbonic-acid gas.

The introduction of ozone brought, however, an immediate change; the induced enhancement of excitability is seen