Amputated apices from vegetative wildtype cells of the uninucleate green alga Acetabularia acetabulum can differentiate a reproductive structure of 'cap' in the absence of the nucleus (Hämmerling, J. (1932) Biologisches Zentralblatt 52, 42-61). To define the limits of the ability of wildtype cells to control reproductive differentiation, we determined when during development apices from wildtyp...