These studies on embryos of rediae of the suborder Echinostomata Szidat, 1939, show that in very early stages the germinal mass consists only of unicellular components, and it is only in later development, after some free embryos are present, that some of the germinal cells form embryos which remain attached for a while to the mass as multicellular components. It can be suggested that at a much earlier stage of the development of the redial embryos a single cell of the germinal line comes to lie just back of the cells that form the intestine. This cell then goes through a series of divisions forming a morula-like mass of germinal cells in the primitive body cavity which later becomes a typcial germinal mass with both unicellular and multi-cellular components.