Page:Life Movements in Plants.djvu/242

This page has been proofread, but needs to be validated.
212
LIFE MOVEMENTS IN PLANTS

Increasing intensity of light induces increasing retardation and arrest of growth. Under continued action of light of strong intensity the growing organ may undergo an actual shortening.

In these reactions the action of stimulus of light resembles the effects of electric and mechanical stimuli.

The ultra-violet rays induce the most intense reaction in retardation of growth. The less refrangible yellow and red rays are practically ineffective. But the infra-red rays induce a marked retardation of growth.

The effects of light and warmth are antagonistic. The former induces a retardation and the latter an acceleration of growth.

This article is issued from Wikisource. The text is available under Creative Commons Attribution-Share Alike 4.0 unless otherwise noted. Additional terms may apply for the media files.