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

SOME PROBLEMS OF REPRODUCTION. 31
The oosphere or "procarp" has a long trichogyne closed at the
apex, and a basal enlargement containing the single nucleus.
The spermatium adheres to the trichogyne and opens into it ; l
its contents with the male pronucleus pass down j and since
at this time two nuclei are seen in the base of the procarp, and
only one shortly after, it is certain that the nuclei must fuse
in the zygote. The trichogyne is then shut off, its lumen
being encroached upon to obliteration by a centripetal growth
of its cell-wall close to the base. Before and after fertilisation
granules which react to stains like nuclear chromatin are
present in the plasma of the trichogyne; and Schmitz
identifies these with excreted nuclear fragments on purely
& priori grounds, relying on the current theory of fertilisation.
But he adduces no real evidence as to their origin and
nature.
A peculiar process occurring in many Florid ese is secondary
fertilisation, the zygote forming a new karyogamic
union as a gamete with an " auxiliary cell" or secondary
oosphere; or the zygote grows and branches with cell division,
and its offspring play the part of secondary males to the
secondary oospheres (Dudresnaya). In this way sometimes
one spermatium indirectly fertilises several secondary oospheres
—an economical process as yet unparalleled in nature; its
explanation is probably to be sought in the motionless character
of the male cells, and the inadequate adaptations for what
we may almost term " pollination."
In CoftALUNA the procarps with their auxiliary cells are
collected into a disc; the central cells alone possess trichogynes,
and are fertilised by the spermatia; but as zygotes they
have no power of development save to fertilise in turn the
peripheral procarps, which have no receptive organs of their
1 The following cjtological details are taken from the account by Schmitz
in ' Sitzuugsber. d. Berl. Akad.,' 1883, 215.