And it must be remembered that it is only an assumption which places the Orthonectides among the lowest Metazoa (Heteroplastids). I do not intend to greatly emphasize this point, but the formation of the Gastrula by embole, and the absence of a mouth and alimentary canal, shows that these parasites are extremely degenerate, and the same may be said of almost all endoparasites. The Gastrula, as an independent organism, was without doubt primitively provided with both mouth and stomach, and the mass of ova filling the female Orthonectid is an adaptation to a parasitic life, which on the one side renders the possession of a stomach a superfluity, and on the other demands the production of a great number of germ-cells[78]. It is certain that the Orthonectides, as at present constituted, cannot have lived in the free condition, and also that their adaptation to parasitism cannot have arisen at the beginning of the phyletic development of Metazoa, because they inhabit star-fishes and Nemertines—both relatively highly developed Metazoa. Hence it is, at any rate, doubtful whether the Orthonectides can claim to pass as typical forms of the lowest Heteroplastids, and whether their reproduction can be looked upon ‘as typical for the unknown ancestors of all Polyplastids’ (l. c., p. 45). If, however, we accept some organism resembling these Orthonectides as the most ancient Heteroplastid, being a free-living organism, it must have had a stomach, and the cells surrounding it must—as a whole or in part—have possessed the power of digesting; at any rate, they cannot all have been germ-cells, and therefore it is improbable that death would be the direct result of the extrusion of the germ-cells.