IN view of recent publications in the United States, it is desirable to record briefly some of the results obtained by us during the past year or so. Following the demonstration by LaForge and Barthel1 of the heterogeneity of ‘pyrethrolone', the alcoholic component of the pyrethrins, and the revision by LaForge and Soloway2 of e structures of the constituent alcohols to (I), where R is butenyl or pentadienyl, and the synthesis by Campbell and Harper3 of (—)-trans-chrysanthemum monocarboxylic acid (II), the enantiomorph of the acidic component of pyrethrin I, the total synthesis of various pyrethrins (that is, esters of I with II), the insecticidal constituents of pyrethrum flowers, appeared a more favourable project than previously.