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The fertilized egg-cell, formed by the union of egg and spermatozoon, is a single cell, like the individual resulting from the conjugation or fusion of two protozoa. But in the many-celled individual, which develops out of the fertilized egg, there are two kinds of cells. 1.
Isolated cases show that any of the cells within the embryo-sac may exceptionally form an embryo, e.g. the synergidae in species of Mimosa, Iris and Allium, and in the last-mentioned the antipodal cells also. In a species of Allium, embryos have been found developing in the same individual from the egg-cell, synergids, antipodal cells and cells of the nucellus.
All differentiations of his body, from the first differentiation of the egg-cell into a complexity of cells up to the last formation of his organs, take place in the same gliding development. All his psychical and spiritual functions and forces come into existence in this form of gradual development.
The wax is chocolate-coloured, and almost the only difference I can find in the economy of the two species is that the black bee uses a large quantity of wax in plastering the interior of its nest. The egg-cell of the yellow bee always contains from twelve to sixteen eggs; that of the black bee from ten to fourteen; and the eggs of this species are the largest though the bee is smallest.
The brushing seems to disturb the equilibrium of the protoplasmic egg-cell within the egg-shell just sufficiently to set it going going on its course of division and development. The only other case of "artificially-induced parthenogenesis" at present recorded is that of the common frog, due to M. Bataillon. There are questions of great interest still to be made out as the result of his discovery.
With regard to the physiology of the female organs, the following topics should be considered: The meaning of puberty as the beginning of a long fertile period of about thirty years; the nature of menstruation as a periodical process preparing the lining of the uterus for reception and attachment of an embryo if a sperm-cell meets a liberated egg-cell near an ovary, and not as a season of illness invented by the powers of darkness; the possibility of fertilization following sexual relations at any time during the fertile life of a woman; the essential facts of sexual relation as a method of depositing sperm-cells so that they can swim on the way to meet an egg-cell; and the nature of the close blood relationship of mother and embryo.
There it is, developing bit by bit, from one single egg-cell which you were at your conception in your mother's womb, on and on to the strange and peculiar complication in unity which never stops till you die if then. You've got an innermost, integral unique self, and since it's the only thing you have got or ever will have, don't go trying to lose it.
We see, then that the process of fertilisation consists in two things, the latter of which necessitates the former, viz. in the breaking or penetration of the surface of the egg-cell by the active sperm filament and second in the fusion of the substance of the sperm filament with that of the egg in such a way that there is a distinct and intimate fusion of the nucleus of the sperm filament with the nucleus of the egg-cell.
On the other hand, Harvey's dictum, "Every living thing comes from an egg," is only true in a limited sense, namely, that whilst the individual among most larger animals and plants is always traceable to an egg-cell detached from a parental individual of a like kind of species, there are whole groups and series of lower animals and most plants in which the individual born or "developed" from an egg-cell does not proceed when grown to full size to reproduce in turn by eggs and fertilising sperms, but divides into two or more individuals or gives off detached buds or reproductive bulbs, which become separate individuals, and only after these and several successive generations of individuals have been thus produced "asexually," by fission or by budding, does a generation appear which produces true egg-cells and sperm-cells and reproduces by their means.
It drives its way into the substance of the egg, making a minute hole in its surface; then the protoplasm of the sperm fuses with the protoplasm of the egg, and becomes intimately mixed with it. The egg-cell has a "nucleus," that dense, peculiar, deep-lying, and well-marked "kernel" of its protoplasm which all cells have. It is of essential importance in the life and activity of the cell.
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