RELATION BETWEEN LIGHT AND THE ELECTRIC POLARITY OF CHARA

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Abstract
With an especially constructed apparatus the apex of Chara vulgaris was found to be positive electrically to more basal regions. Mechanical stimulation caused the stimulated region to become negative but it returned quickly to the electropositive condition. No evidence of transmission of the electrical effect across the internode was obtained. Illumination of the whole plant caused the apex to become more electropositive. Electro-positivity of any portion of the plant was increased by illumination of that region. Increase of electrical response with increased illumination, no change of the electrical potential in green light and an increase in polarity in light in the presence of CO2 related the change of potential with photosynthesis. The response to light was increased in low and decreased in high O2 concs. The production of O2 available for cellular oxidation by photosynthesis is suggested as a factor in increasing the electrical potential upon illumination.