ELECTRICAL CONTROL OF RHIZOID FORMATION IN THE RED ALGA, GRIFFITHSIA BORNETIANA.
1. Direct galvanic current of 10 to 40 microamperes per square millimeter of cross-section of medium results in anodal determination of rhizoid origin in the differentiated cells of the red alga Griffithsia bornetiana. The current is most effective near the upper end of the range. 2. Within the range used there is an increase in the number of rhizoids produced with increase in current intensity and a decrease in size of rhizoids. 3. Currents of lower intensity require a longer time to produce these effects than comparatively high currents. 4. The orientation of the plants in the electrical field seems to affect the number of rhizoids produced, in that plants with apexes toward the anode produce more rhizoids. 5. Together with anodal rhizoid determination there is migration of chromatophores toward the anodal side of each cell. 6. Displacement of chromatophores (and other cytoplasmic bodies) by the centrifuge does not affect the point of rhizoid origin, but does affect the shoots. 7. Together with anodal determination of rhizoids the algal filaments become graded in color, from bright pink toward the cathode to pale tan toward the anode. 8. Evidence is presented to show that this is not due to a pH change, but to a loss of pigment by chromatophores toward the anode and electrophoresis of the pigment toward the cathode. 9. In conclusion the probability is pointed out that the current acts in morphogenesis by moving particles of different charge.
Schechter
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Department of Biology of The College of the City of New York, New York.