Statoliths in Phycomyces: Characterization of octahedral protein crystals.
The crystals, which are present throughout the central vacuoles of the sporangiophore, function as statoliths.
Absorption spectra of isolated crystals and in situabsorption spectra of growing zones indicate the presence of chromophores, probably oxidized and reduced flavins. The flavin nature of the chromophores is also indicated by their fluorescence properties. It appears likely that the chromophores represent an essential part of the statoliths and thus the gravitropic transduction chain.