Some Problems of Reproduction: a Comparative Study of ...

50 MARCUS M. HARTOG.
matogenygoes on by budding as in mode (6). The spermatozoa
become free and leave behind a uninucleated blastophore,
which is not known to be capable of further growth or division.
We may fairly connect this peculiarity with the attachment of
the spermatogonia in most cases, the nucleated blastophore
serving as an active intermediary for the exchanges between
the wall of the tube and the developing spermatozoa. And
this is a character of adaptation, of no morphological, and of
minor physiological importance. 1 I annex a schema (Fig. 8) of
a spermatogonium of this kind, in which four divisions are
supposed to have occurred. Owing to the fate of one of the
• 2 4 " 1 = 8 spermatozoa.
N N l nucleated blastophore.
Pie. 8.—Schema of spermatogeny, with formation of nucleated blastophore;
Grantia type.
first two nuclei the number of spermatozoa formed at the
nth bipartition of the nucleus is only 2""" 1 , instead of 2",
i. e. only half the normal number.
2, Oogeny.
The Metazoan oogonium, the "ovarian egg" or u ovum" of
authors, is peculiar in attaining an enormous size, owing to its
power of storing up reserve supplies in the form of unorganised
yolk-granules to supply the metabolism of the future embryo;
and, correlated with this, it usually possesses an immense
1 Our interpretation of the nucleated blastophore, as a nutritive organ
rather than as an excretion, is confirmed by the fact that the numerous
broods of Rat spermatozoa, formed by mode («), contract a union with a basal
cell; and this syncytium is undistinguishable from the apocytium of the
Bpermatocytes and nucleated blastophore in mode (c).