Polylysine synchronously aggregated pigment granules and egg surface stained uniformly with fluorescein isothiocyanate to form patches (Plate I, fig 1 & 2). Patches always appeared and aggregated first in the opposite grey crescent region, then in grey crescent region and next at animal hemisphere. A fluorescent ring formed at the upper side of the equatorial region. The ring and the patches at the animal hemisphere accumulated to the animal pole to make a cap (Plate I, Fig. 3). Finally the vegetal hemisphere broke due to the contraction of egg surface during aggregation. These indicated that four different domains: opposite grey crescent region, grey crescent region, animal and vegetal hemispheres, were present at the fertilized egg surface. Similar domains also occurred at the unfertilized egg surface as revealed by the same treatment suggesting that the opposite grey crescent region of fertilized egg, which corresponding to the sperm entrance region had existed at the mature egg surface. There were three modes in the early stage of patch formation: (1) the features of granular protrusions did not change greatly (Plate I, Fig. 5-7), (2) the granular protrusions elongated (Plate I, Fig 8-11) and (3) folds radiated from patch (Plate I, Fig. 12, 13). Around each patch new surface membrane arose, which was similar to the nascent membrane of cleavage furrow.(ABSTRACT TRUNCATED AT 250 WORDS)