Treatment of slices of young pea leaves (Pisum sativum) with gM solutions of a-chloralyl diethyldithiocarbamate, dichloroalHyl diisopropylthiocarbamate, or S-ethyldipropylthiocarbamate resulted in inhibition of incorporation of [1-V4C] Certain thiocarbamates were reported to be inhibitory to wax production on foliage (4,5,12). Experimental evidence thus far available shows that fatty acid elongation is a key process involved in cuticular wax synthesis (2, 10). Recent ob-servation that thiocarbamates inhibited synthesis of C., to C.4 fatty acids in germinating seeds (6) the thiocarbamate in a total volume of 0.5 ml of water. After the contents of the flask were thoroughly mixed, the leaf slices were spread on the bottom of the flasks which were then incubated for 90 min at 30 C in a gyratory water bath shaker. At the end of the incubation period the tissue slices were transferred into a 150-ml sintered glass funnel and 100-ml of a 2:1 mixture of chloroform and methanol was added. After stirring the mixture for 20 sec, the solvent mixture was quickly removed by suction. The lipids were recovered from this solution according to the method of Folch et al. (3), and this fraction is referred to as surface lipids. The tissue slices were then extracted with a 2: 1 mixture of chloroform and methanol for 2 hr, and the lipids recovered from this extract are referred to as internal lipids.Fractionation of Lipids. Surface lipids were dissolved in 0.5 ml of chloroform and 10 ,ud were used for determination of radioactivity. Fifty ulI were subjected to TLC on 0.5-mm layers of Silica Gel G with benzene as the developing solvent. The plates were sprayed with a 0.1% alcoholic solution of 2',7'-dichlorofluorescein and the components were marked under UV light. (In order to aid in the visualization of the components on the thin-layer plates, unlabeled surface lipids were added to the labeled material prior to chromatography.) Radioactivity in each fraction was determined by scintillation counting of the silica gel from appropriate areas as described before (7

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