LAYER growth on crystals was observed by Marcelin1 and other workers. Steps on crystals could be produced by surface nucleation or by the presence of screw dislocations which terminate at the surface2. The layers on cadmium iodide growing in aqueous solution3 were shown by Forty4 to be steps originating from dislocations. While Bunn3 was unable to find any layers on growing sucrose crystals, Powers5 observed them but without seeing any definite signs that they were due to screw dislocations. We have made an extensive examination of the surface features of sucrose crystals grown in the temperature-range 15–30° C. and conclude that the normal growth process is that described by Frank2. Step systems in the form of growth hills have been shown to be present on all faces of sucrose crystals when grown in pure sucrose solution and in sucrose solution with added dextrose or lævulose as impurity. Crystals grown in sucrose solution with added dextrose (0.2 per cent by weight of the sucrose) have steps which generally are much larger (about 40 times) than those grown in pure solutions of sucrose or in solutions with added lævulose.