Persistence of Pyrethrins and Gamma Isomer of Benzene Hexachloride

Abstract

IN reply to the queries raised by Mr. Beckley, I should like to record that the experiments described in my original letter were carried out merely to compare the toxicity and persistence of pyrethrins and gamma benzene hexachloride under similar conditions. The dusted wheat was contained in 2-oz. glass jars covered with organdie muslin and packed closely together in a wooden tray, 2½ in. deep. The experiment was conducted in a constant-temperature room having a small window facing north-east. Consequently, only very weak, diffuse light reached the dust scattered among the wheat grains.