of the manner of the multiplication of the cells of Conferva.
Moreover, the investigations of MM. Dumortier and Hugo
Mohl do not go further than to prove, except perhaps the
remarks of the latter in reference to one species of the genus
Zygnema, that the terminal cell of each filament is successively
undergoing division, and not the far more important fact
upon Avhich I have so particularly dwelt, tha t all the cells of
a Conferva or articulated Alga are constantly and almost
simultaneously undergoing a similar process of multiplication
by division.
M. Morren afterwards observes in his le ctu re: “ In my
memoir on the Closteria, inserted in the “ Annales des
Sciences Naturelles (partie Botanlque), Mai, 1836,” I showed
th a t the colouring matter, the endochrome, in consequence of
polarization, divides itself in each cell into two opposite
masses, which become separated by the secretion of a transparent
liquid (a true intercellular substance, in which is
formed the double diaphragm, which hy separating produces
slowly the dislocation of the two cones of the Closterium.
“ I have since observed,” continues M. Morren, “ all the
particulars of this phenomenon of the formation of intermediate
partitions in the Conferva, my observations having been
made on Conferva dissiliens. The articulations in this are
very short, equalling their diameter or even less than this.
N oav there is in these a green mass at first uniform, in which
appear peculiar globules, which become transparent vesicles,
more yelloAV than the rest of the colouring matter, presenting
finally spots more obscure, almost broAvn or red at the centre.
These bodies appear to me to be the male apparatus exercising
a true fecundation upon tlie rest of the endochrome.
But this mass, Avhen the male cellules are developed, polarizes
and floAvs toAvards the tAA’o poles of the parent or general
cell. Then this cellule is seen to become elongated under
the dominion of this ebbing or polarization, and between
these tAvo masses a transparent space is manifest. The com-
pressorlum has proved to me that there is here a mucous
fluid or intercellular substance. Now upon the periphery of
this substance the condensation operates; at first little by
little it proceeds toAvards the centre, and in place of a zone of
liquid substance there is a membrane duly organized and
fit to become divided into tAVO membranes, each mass of
endochrome having its wall, or more correctly, its proper
membrane.” In this account no mention is made as to
Avhether the cells, the division o f Avhich M. Morren witnessed,
Avere terminal or not.
jMy own vieAvs of the phenomenon of the division of the
cells of Conferva, and of the explanation to be offered of it,
differ considerably from those of M. Morren. All the cells
of a Conferva, until it has reached a state of maturity, are
continually increasing in length; and it is only in certain cells
Avhich have exceeded their standard length, that the gradual
separation of the endochrome into tAvo masses is seen to
occur, and a transparent space to be left betAveen th em ; this
space is not, hoAvever, in my opinion, occupied by any formative
intercellular matter, such as tha t referred to hy M.
Morren, Avho, in his explanation, asserts that the polarization
and separation of the endochrome fir s t takes place, and that
afterAvards the cells begin to grow. The first indication of
the formation of the partitions which are to divide the parent
cell into two, is not visible until after the separation of the
endochrome, and appears to consist in a solution of a portion
of the periphery of the centre of th a t cell, the divided edges
of the cell then becoming inverted separately, and growing
towards the centre, where they coalesce. Thus, according to
this vicAv, the partitions of the cells are not, as M. Morren
would assert, ncAV grov/ths or formations, but merely an
extension of the separated margins of the parent cell.
A second mode of development *, of considerable importance
as regards the classification and description of the Alga,
still remains to be described. In many species of Conferva
more especially in the branched kinds, and in numerous other
A lg a ; in the species of the genera Vesiculifera, Lyngbya,
Meloseira, Fragilaria, &c., there is not only a longitudinal developement
of the cells, but there is likeAvise a lateral groAvth
* See Annals of Nat. Hist. vol. xi. p. 359.
D