Meiosis and sporulation induced in sporophytes of Ulva mutabilis ("slender") with synchronous mitosis.

Sporulation preceded by meiosis was induced in young, diploid plants of Ulva mutabilis, mutant "slender" (FöYN). The induction was brought about either by replacement of the old culture medium (sea water plus soil extract) with new, or by the addition of a mixture of seven vitamins to old medium. The new chemical environment seems to induce a shift from presumptive mitosis to presumptive meiosis.