That M. G. Thuret is in error in uniting all the species of
Vaucheria into one, will, by a reference to the descriptions
and figures of the genus Vaucheria, which accompany this
Avork, be at once perceived.
The animalciAles contained in the cells o f the filaments,
Avhich occupy the interior of the globule of Chara, bear
considerable resemblance to the zoospores of the A lg a ;
like them, OAving their power of locomotion to the presence
of cilia, the anterior extremity of each being furnished with
tAVO long lashes or cilia (see plate 62., Jig. 5, 6.). I f the
AdcAVS of physiologists, hoAvever, respecting them be correct,
an essential and functional distinction exists between
them; the one being the sporules themselves, and the other
the organism, or instruments, whereby those sporules are
fertilized.
While the term zoospore has been applied to the moving
sporules of the Alga, the appellation of sjiore has been conferred
by some Avriters upon the large and usually elliptical
body formed in the different species of the genera Zygnema*,
Tyndaridea, Staurocarpus, Mesocarpus, Mougeotia, Vesiculifera,
and perhaps Bulbochate, by the union and consolidation
of the contents of two cells either in the same or
different filaments. Concerning the nature of this body,*
considerable difference of opinion has prevailed and still
obtains. Vaucher, who has so accurately described numerous
species of Conjugata, thus speaks of i t :—“ A tla s t,
on the 25th Messidor, an IX , in examining the remains of
the Conferva jugalis Muller, Avhich I had folloAved since
the commencement of spring, I arrived fully and without
any doubt at this tru th so desired, and which I had made
so long and so fruitlessly the object of my researches.
Almost at the same instant, and in the same day, or at least
in the same week, all the grains of the Conferva jugalis, of
Avhich I had many thousands, opened themselves by one of
their extremities. In the same manner as the tAVO cotyledons
of a seed Avhose embryo has become developed ; and from the
* See the figures of those genera.
base of the aperture there issued a green sac, at first very
small, but AAdiich soon extended Itself in such a manner tha t it
surpassed many times the length of the globule. In the
interior of this sac appear soon the spires, they being accompanied
by their brilliant points, as in a Conjugata enthely
developed. The tube itself exhibits divisions, at first one,
aftei’Avards tAvo, then a great number; at last the Conjugata
detaches itself from Its grain, and floats alone in the liquid,
and then nearly in size, and with two extremities, Avhich are
still pointed, it resembles perfectly the plant Avhich gave it
birth.” In this description Vaucher is doubtless altogether
in e rro r; and it is difficult to conceive in what way he could
have been so imposed upon, a careful microscopic examination
of the “ spore ” alone being quite sufficient to convince the
observer that no such dehiscence as that represented by
Vaucher could take place. M. Deeaisne * regards these
bodies as the true and only germs of the Conjugata or
Sunspores, as he has denominated them in removing them
from Agardh’s extensive class of Zoospores. Mr. Jenner, an
indefatigable and excellent observer, Avrites me word that he
has Avituessed the groAvth of these “ spores,” “ Avhich is, by a
general extension of the whole investing membrane or
membranes, Avhich subsequently divides and subdivides into
other cells; ” and Kfitzing also, if I mistake not, states that
he has been a witness of their developement in Zygnema and
Vesiculifera, or (Edogonium. Agardh thus writes in the
memoir before alluded to concerning them in the Conjugata,
he not being acquainted Avith the fact of their formation in
the true Conferva; —“ During the conjunction of a Conjugata,
one of the filaments is always giving, the other always receiving
; the spires of the giAung filament first become
confused; and it is not rmtil after the entrance of the matter
of that filament that they become irregular in the other, and
then the tAvo masses become confounded together, to form
the elliptical or spheroidal bodies. The globules of which
the spires are composed do not clear themselves the one from
* Annales des Sciences Naturelles, Mai, 1842.
c 4