IN the cytoplasm of the oocytes of Aplysia depilans L. (Mollusca, Opistobranchia), during the first phases of growth, a large quantity of Golgi bodies or dic-tyosomes can be found. Such bodies can be observed with the optical microscope with the silver impregnation methods and they are generally arranged along a bent line (Fig. 1). The same bodies can also be observed with the electron microscope (Fig. 2), and in this instance they show a closed system of double parallel membranes (Fig. 5) and not an open system, as generally observed by previous authors. Inside these bodies1 there are vacuoles with a clear content and vesicles with a dark content, which correspond to similar structures of the open system. In the oocytes of Aplysia vitellogenesis takes place following a radical transformation of Golgi bodies into yolk globules, as already observed by Parat2 in Aplysia punctata.