Samples from synchronized cultures of Rlastorlacliella e m e ~ s o n i i were examined by electron microscopy from t,he late log phase to the completioli of zoospore differentiation, Log-phase plants contain t,he usual cytoplasmic organelles but also have an unusual system of large tubules ca. 45 mp diam that ramify in organized bundles throughout the protoplast,. After induction, zoosporangium...