Nevertheless, that there are great distinctions between true sexual propagation and this foreshadowing of it in conjugation I do not deny. The question, however, is whether they be so great as to justify any argument against an historical continuity between them. What, then, are these remaining distinctions? Briefly, as we have seen, they are the extrusion from egg-cells of polar bodies, and the occurrence, both in egg-cells and their products (tissue-cells), of the process of karyokinesis. But, as regards the polar bodies, it is surely not difficult to suppose that, whatever their significance may be, it is probably in some way or another connected with the high specialization of the functions which an egg-cell has to discharge. Nor is there any difficulty in further supposing that, whatever purpose is served by getting rid of polar bodies, the process whereby they are got rid of was originally one of utilitarian development--i. e. a process which at its commencement did not betoken any difference of kind, or breach of continuity, between egg-cells and cells of simpler constitution. Lastly, with respect to karyokinesis, although it is true that the microscope has in comparatively recent years displayed this apparently important distinction between unicellular and multicellular organisms, two considerations have here to be supplied. The first is, that in some of the Protozoa processes very much resembling those of karyokinesis have already been observed taking place in the nucleus preparatory to its division. And although such processes do not present quite the same appearances as are to be met with in egg-cells, neither do the karyokinetic processes in tissue-cells, which in their sundry kinds exhibit great variations in this respect. Moreover, even if such were not the case, the bare fact that nuclear division is not invariably of the simple or direct character in the case of all Protozoa, is sufficient to show that the distinction now before us--like the one last dealt with--is by no means absolute. As in the case of sexual propagation, so in that of karyokinesis, processes which are common to all the Metazoa are not wholly without their foreshadowings in the Protozoa. And seeing how greatly exalted is the office of egg-cells--and even of tissue-cells--as compared with that of their supposed ancestry in protozoal cells, it seems to me scarcely to be wondered at if their specializations of function should be associated with corresponding peculiarities of structure--a general fact which would in no way militate against the doctrine of evolution. Could we know the whole truth, we should probably find that in order to endow the most primitive of egg-cells with its powers of marshalling its products into a living army of cell-battalions, such an egg-cell must have been passed through a course of developmental specialization of so elaborate a kind, that even the complex processes of karyokinesis are but a very inadequate expression thereof.