For the study of the process of latent image formation by the arrested development technique, a new method for making a replica for electron micrograph was developed by using a monodisperse and mono-grainlayer emulsion. The topography of development centers was also studied by this method. The sites of development centers observed in the grain surface are classified to front, back, side and edge of cubic grains for incident light. The distribution of development centers are somewhat different between fornt and back. At lowex posure more centers are formed on side than front or back, and at high exposure more centers are formed on front or back than side.