The scheme of this formation of the polar bodies is indicated in Fig. 10, p. 45. In Fig. 10_b_ the chromosomes are seen paired and ready for the first division; that is, for the formation of the first polar body. Figs. 10_c_, _d_, p. 45, show the giving off of this body. Note that while only a small proportion of the cytoplasm passes into this tiny cell, its chromatin content is as great as that of the ovum. A second polar body (Figs. 10_e_, _f_, p. 45) is formed by the egg, but in this case each chromosome splits lengthwise, as in ordinary mitosis, and there is no further numerical reduction. In the meantime, typically, a third polar body is formed by division of the first. (Stages _e_, _f_, _g_.) =Parallel Between the Maturation of Sperm- and Egg-Cell.--=This rather complex procedure of the germ-cells will be rendered more intelligible through a careful study of Figs. 9 and 10, pp. 42 and 45, and Fig. 11, p. 46, which indicates the parallel conditions in spermotogenesis and oögenesis. [Illustration: FIG. 10 Diagram to illustrate oögenesis: _a_, showing the diploid number of chromosomes (six is arbitrarily chosen) as they occur in ordinary cells and oögonia; _b_, the pairing of corresponding mates preparatory to reduction; _c_, _d_, reduction division, giving off of first polar body; _e_, egg preparing to give off second polar body, first polar body ready for division; _f_, _g_, second polar body given off, division of first polar body completed. The egg nucleus, now known as the female pronucleus, and each body contain the reduced or haploid number of chromosomes.] The view now generally held regarding the polar bodies is that they are really abortive eggs. They later disappear, taking no part in embryo-formation. It can readily be seen how such an unequal division is advantageous to the large cell, for it receives all of the rich store of food material that would be distributed among the four cells if all were of equal size. This increased amount of food is a favorable provision for the forthcoming offspring whose nourishment is thus more thoroughly insured. [Illustration: FIG. 11 Diagram showing the parallel between maturation of the sperm-cell and maturation of the ovum.] On the other hand, all of the sperm-cells develop into complete active forms, which, as aforesaid, usually become very much elongated and develop a motile organ of some kind. In such cells an accumulation of food to any large extent would hinder rather than help them, because it would seriously interfere with their activity.