photodromy

In the induced or spontaneous clarification of certain suspensions, the settlement of particles on the side nearest the light (positive p.) or on the dark side (negative p.). [photo- + G. dromos, a running]

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pho·tod·ro·my (fo-todґrə-me) [photo- + Gr. dromos running] the phenomenon of moving toward (positive p.) or away from (negative p.) light, as in the case of particles in suspension.