Phototropic Equilibrium in Phycomyces

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Science  20 Mar 1959:
Vol. 129, Issue 3351, pp. 775-777
DOI: 10.1126/science.129.3351.775-a


When illuminated by two light sources, the positively phototropic sporangiophores of Phycomyces blakesleeanus come into a state of phototropic equilibrium. In this state, the sporangiophores assume an orientation determined by the light fluxes falling upon opposite sides of their light-sensitive zones. Under certain conditions, the sporangiophores show tropic oscillations about the equilibrium direction.