. The nucleus of the spermatozoid, on the contrary, begins
to grow rapidly. It forms half the number of chromosomes
corresponding to the cell of the species to which it belongs, and
grows at the expense of the vitellus of the egg. During this time the
centrosome divides into two halves, which progress slowly on each side
toward the periphery of the egg, as in the case of fission (see Plate
I), while the chromatin of the chromosomes of the spermatozoid is
dissolved in the network. The nucleus thus formed by the spermatozoid
enlarges more and more (Figs. 13 and 14) till it attains the size and
shape of that of the egg (Fig. 15). The male and female chromatin are
colored red and blue respectively.

Then only commences activity of the nucleus of the egg, at the same
time as fresh activity on the part of the nucleus of the spermatozoid.
Before this, however, the nucleus of the egg has thrown off a part of
its chromatin called a _polar_ body, and it now possesses only half as
much chromatin as the other cells of the body of the individual. The
nucleus of the egg and that of the spermatozoid then begin at the same
time to concentrate their chromatin in the form of chromosomes (Fig.
16) which arrange themselves regularly in the middle line exactly as
shown in Plate I, and divide longitudinally into two halves which are
then attracted in opposite directions by the rays of each of the
centrosomes (Fig. 17). Figure 17, of Plate II, thus corresponds
exactly to Fig. 6, of Plate I.

In fact, the growth of the nucleus of the spermatozoid has given to
its substance the same power of development as to that of the nucleus
of the egg. Both enter into conjugation in equal parts, which
symbolizes the social equality and the rights of the two sexes!

The signification of these facts is as follows: as soon as, in the
course of development, the conjugated nuclei divide again into two
cells, as in Figs. 7 to 10, of Plate I, each of these two cells
contains almost the same quantity of paternal as maternal chromatin.
We do not say exactly as much, for the paternal and maternal
influences are not divided equally in the descendants. This phenomenon
may be explained by what _Semon_ calls alternating ecphoria in mnemic
dichotomy. (_Vide infra._) As cell division continues in the same way
during embryonic life, it follows that each cell, or at least each
nucleus of the future organism, will contain on the average half its
substance and energy from