[95 1 THE CUTICULAR WATERPROOFING MECHANISM OF THE WORKER HONEY-BEE

lipoid material which is present on or near the outer surface of insect cuticle serves to restrict the evaporation of water from the animal. Existing knowledge of the nature of this waterproofing layer has been built up from observations on the effect of dusts, heat, detergents and organic solvents on the rate of evaporation from intact cuticle and also from a study of the changes in permeability of natural and artificial membranes when coated with thin layers of lipoid material. This paper describes experiments undertaken to obtain information on the nature of the waterproofing layer in the worker honey-bee. PART 1. THE ACTION OF DUSTS ON WORKER HONEY-BEES Alexander et al. (1944 a) demonstrated that certain dusts were lethal to insects by virtue of their physical properties, and that this was due to their action in promoting water-loss. Wigglesworth (1944, 1945) showed that dusts can abrade the surface lipoid layer of the insect's cuticle thereby increasing the rate of water-loss through the cuticle. Beament (1945) and Alexander et al. (1944c) found that certain dusts could adsorb artificial wax films deposited on such substances as tanned gelatin whic