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the other during the slow emanation of the matter from the
giving filament, and no trace of other motion is observed
amongst them. On the contrary, it is in the elliptical body,
constituted by the mingled contents of tAvo joints, tha t I
believe to have recognized a phenomenon of locomotion
analogous to that described previously in reference to Conferva
area. After many fruitless researches, made for the
purpose of seeing the elliptical body develope itself into a
ncAv filament, as Vaucher has described, I clearly saw them,
on the contrary, dissolve into numerous sporules, endoAved
Avith a very rapid motion. Apart from the phenomenon of
union of the filaments, which distinguishes the Conjugata
from all other Alga, the only peculiarity in their propagation
is, tha t the elliptical bodies from which the sporrdes proceed
remain after many months without any change in them,
Avhile they dissolve immediately in the true Conferva.” My
OAvn vicAV of the nature of these elhptical bodies precisely
coincides Avith that of Agardh. They are to be considered, I
think, as so many sporangia stored with zoospores, which
they retain together and preserve from injury until the
period proper for their developement arrives. Each of them
is composed of at least two, and, according to Meyen, three
membranes, these being formed by the gradual inspissation
of the organic mucus enveloping the zoospores. A t all
events, if they be not sporangia, and if they ever germinate,
as some suppose, but Avhich I consider still to be very questionable,
a second mode of reproduction, which some have
contended for, must he conceded to those plants possessing
them ; for it is very certain that the Vesiculifera,in the different
species of which are formed bodies in all respects analogous
to those of the Conjugata, are propagated principally, if not
exclusively, by zoospores. This is undeniable, and it is but
consistent with analogy to suppose, as Agardh has asserted,
tliat the Conjugata are perpetuated in the same manner.
The observation tha t they dissolve immediately in true Confe
rva , does certainly not apply to the true oval or circular
organs formed in the true Conferva, with the existence of
which Agardh was not acquainted. These are, in all respects.
similar to those of the Conjugata, and are no less permanent
in their nature. •
M. Deeaisne combats the idea of the disintegration of the
spores of the A lga formed by the union of the endochrome
of two cells into zoospores. He states the fact, tha t the
contents of the spores are fluid. This argument is, however,
by no means conclusive ; the contents of the undoubted
zoosporous A lga are, also, for the most part, fluid; Avhen,
hoAvever, the full developement has been attained, the fluid
disappears, and the cells are filled with zoospores. The same
may occur in the spores of the Zygnemata &c., as asserted to
be the case by Agardh.
hi. Deeaisne also, in his “ Memoir on the Classification of
the Alga,” strongly repudiates the idea of a double mode of
reproduction. The spores, M. Deeaisne regards, as already
remarked, as the true and only reproductive bodies of those
Alga in Avhich they occur, and asserts that in these Alga
zoospores are never formed. M. Deeaisne thus clearly expresses
himself on this point : “ Mais je crois pouvoir avancer
aujourd’hui que les zoosporées n’offrent jamais de corps reproducteurs
résultant d’une concentration de la matière verte
provenant de deux individus.”
This generalization of M. Deeaisne Is surely untenable, for
it Is perfectly certain tha t the usual and most frequent mode
of reproduction of the Vesiculifera, in which spores altogether
analogous, as before stated, with those of the Conjugata
are formed, is by means of zoospores. The motion and developement
of the zoospores of this genus of A lga I have repeatedly
witnessed, in such a manner as to preclude all doubt
on the question. Now this fact in reference to the Vesiculifera,
Avhich may be relied on, leads to the adoption of one of the
folio Aving views, either tha t there is a double mode of reproduction
in at least a certain number of those A lga in which
true spores are formed, viz. by zoospores and spores, or else
that the oval bodies termed spores do become disintegrated,
in accordance with the statement of Agardh, into numerous
zoospores. On the “ spores ” themselves M. Deeaisne has the
folloAving remarks : “ After the complete organization of the