this formation. Frequently it is so concealed beneath the
green granular mass, that it cannot be seen without some
trouble : sometimes it lies near to or between both divisions
of the green mass, and then more easily comes into sight ; but
at the same time it is observable, that it remains unaltered,
and is foreign to the whole of the slimy structure described
above. The latter seems only so far to have a relation to it,
tha t its point of concentration is always at the place where
the nucleus lies, and indeed between it and the walls of the
mother cell.”
Subsequently, the two masses become divided into four,
and the reticulated appearance produced by the spreading of
the masses subsides into radii, which are similar in aspect to
those emanating from the cytoblast in the Zygnemata, each
arising separately from the masses, and terminating on the
inner surface of the cell. Finally, each radiated mass becomes
a perfect spore or cell, separated from each other by distinct
cellular walls, in which changes similar to those ju st described
take place for the production of other spores. The great
similarity in the structure of the incipient spores in the genus
Anthoceros with tha t of the radiated organs in Zygnema,
would lead to the supposition that they were identical in their
nature ; so far, hoAvever, from this being the case, I consider
that all analogy between them terminates with the outward
resemblance. The difficulties in the Avay of regarding the
structure in Zygnema as an incipient germ or spore, appear to
me to be insuperable ; for the question would immediately
arise, wherefore is it, tha t since the contents of two cells
generally go to form a single spore in the genus Zygnema,
and since this radiated organ is present in every cell, that the
one is suppressed, while the other is destined to give birth to
the future Zygnema? Supposing, however, a satisfactory
solution of this difficulty to have been made, still another
arises. I t is far from being an incontrovertibly established
fact, that the elliptical body formed in Zygnema by the concentration
of the matter of two cells, and usually denominated
a spore, does really contain hut a single germ. I t is far
more consistent with known facts to suppose that they are
sporangia filled Avith fertilized sporules; for this is certain,
that numerous zoospores are formed within each cell, and
Avhich may even be seen through the membrane of the sporangia
themselves by the aid of a good glass, these zoospores
being also identical Avith the brilhant granules of the Alga.
The highly interesting observations of Mohl on the genus
Anthoceros, the accuracy of Avhich is in no respect questioned
by me, do not therefore occasion any modification of the
vicAVS expressed of the functions of the radiated organ in
Zygnema.
In October, 1843, I learned that Kutzing, in his “ Phy-
cologia Generalis,” published in August of the same year,
had noticed and figured the cytohlastic organ ju st described;
and tha t Meyen had also previously observed i t ; where,
hoAvever, this is recorded, I cannot ascertain. Kutzing thus
speaks of i t : “ Meyen has discovered in the Spirogyra a
a peculiar central organ. In Sp. nítida it occurs in the middle
of each cell, but is here only to be easily seen in such cells as
are larger than ordinary ; and, from th a t cause, present more
lax spiral bands. By employing the tincture of iodine, one
observes these bodies more easily. Each organ becomes,
together with the delicate threads to which it is appended,
coloured brown by it. I t consists of a (Schwal-gedriicken)
slightly compressed gonidium, through which may be seen a
peculiar nucleus in the midst, and a number of A^ery fine
filaments, which extend from it, in a stellate manner, on all
sides, and are fastened internally to the spiral bands. A t
the place where they are attached to these last, their points
become somewhat expanded. By means of these stellate
filaments the central body becomes suspended in the centre
of the cell. M. Schlelden calls these bodies cytoblasts, and
is of opinion th a t the so-called nucleus threads, to which they
are attached, are nothing else than very delicate streams of
sap, which proceed from the cytoblast, and return to it.
Without wishing to throw doubt upon this pretended flow
of sap, I must, nevertheless, own th a t I have not been able
to observe it with a microscope of Schiek’s or Phoflschen’s
manufacture; hut I have observed th a t the rays of Meyen’s