Anthers of different species of the generaAnemone, Clematis, PapaverandNicotianawere cultured by floating on a liquid medium which overlay an agarified charcoalmedium. This technique proved to be superior to conventional methods i.e. culture on either solid or liquid media. Cold treatment ofAnemoneanthers for 7 days after inoculation on the double layer medium gave about the same frequency of embryos per anther as corresponding cultures cold treated before inoculation. An elevation of the CO2concentration to 2% stimulated embryogenesis in anther cultures ofAnemone canadensis, Anemone vitifolia, Papaver setigerumandPapaver radicatum. Cold treatment of cultures ofAnemone canadensisinhibited embryogenesis if the ensuing culture was performed in 2% CO2.On the other hand, cold treatment was stimulating, with an optimum of about 20 days, if the cultures were maintained in normal air. Chemical analysis of untreated anthers ofAnemone canadensisshowed the presence of abscisic acid (2.2 × 10−6g/g anthers). Cold treatment reduced the concentration of abscisic acid to 0.6 × 10−6g/g anthers. By use of assays withLemna gibbaas test organism, activated charcoal was shown to adsorb abscisic acid that was added to the medium. Medium treated with charcoal before inoculation of anthers ofAnemone canadensisprovided to inhibit embryo produ