At this point it is advisable to return once more to the derivation of death in the Metazoa from the Orthonectides, as Götte endeavoured to derive it, when he overlooked the fact that, according to his theory, natural death is inherited from the Monoplastids and cannot therefore have arisen anew in the Polyplastids. According to this theory, death must necessarily have appeared in the lowest Metazoa as a result of the extrusion of the germ-cells, and by continual repetition must have become hereditary. We must not however forget that, in this case, the cause of death is exclusively external, by which I mean that the somatic cells which remained after the extrusion of the reproductive cells, were unable to feed any longer or at any rate to an adequate extent; and that the cause of their death did not lie in their constitution, but in the unfavourable conditions which surrounded them. This is not so much a process of natural death as of artificial death, regularly appearing in each individual at a corresponding period, because, at a certain time of life, the organism becomes influenced by the same unfavourable conditions. It is just as if the conditions of life invariably led to death by starvation at a certain stage in the life of a certain species. But we know that death arises from purely internal causes among the higher Metazoa, and that it is anticipated by the whole organisation as the normal end of life. Hence nothing is gained by this explanation founded on the Orthonectides, and we should have to seek further and in a later stage of the development of the Metazoa, for the internal causes of true natural death.