IncubationofdinoflagellateCrythecodiniumcohniichromosomesincytoplasmicextractsofunfertilizedXenopuslaeviseggsresultedinchromosomesdecondensationandrecondensation,nuclearenvelopeassembly,andnuclearreconstitution.DinoflagellateCrythecodiniumcohniiisakindofprimitiveeukaryotewhichpossessesnumerouspermanentlycondensedchromosomesanddiscontinuousdouble-layerednuclearmembranethroughoutthecellcycle.Theassemblednuclei,beingsurroundedbyacontinuousdoublemembranecontainingnuclearporesandtheuniformlydispersedchromatinfibersaremorphologicallydistinguishablefromthatofDinoflagellateCrythecodiniumcohnii.However,incubationofdinoflagellateCyrthecodiniumcohniichromosomesintheextractsfromdinoflagellateCrythecodiniumcohniicellsdoesnotinducenuclearreconstitution.