a n
F am . IX . C Y S T O S P E R M EÆ .
Char. Filaments simple, subulate, non-conjugating. Cells at
fir s t equal, subsequently here and there inflated or vesicular.
Sporangia formed by the union and condensation o f the
endochrome o f two contiguous cells o f the same filament.
The impression Avhich I first entertained respecting the Confervoe
contained in this family was, that it would be sufficient
to regard them as constituting a new genus, referrihle to the
Conjugateoe already described: subsequent reflection and examination
have, however, convinced me that they should hold a
higher than a generic rank, and that the characters presented
by them are sufficiently distinctive to entitle them to the rank
of a separate family.
Their filaments are simple, sligh tly subulate, OAving to
the cells groAving laterally, or in diameter as Avell as in longitude,
usually attached, do not conjugate, are articulated or
jointed, and terminate in lanceolate extremities: in their y oun g
condition the cells are uninflated ; subsequently, hoAvever, certain
ones SAvelled up, this inflation being occasioned b y the
transference into them o f the contents o f one o f the adjoining
cells, and in these inflated cells, ultimately are formed, large
oval or circular bodies, similar to those o f the Conjugateoe, both
in appearance and nature, and which therefore I in like manner
denominate sporangia.
In addition to these essential characters o f this family, the
Cgstospermeoe are distinguished by other, though less obvious,
not less important characteristics. The filaments are of a
firmer texture than those of most other Confervoe, they possess
comparatively but little flexibility, are not mucous, and consequently
do not exhibit that glossy appearance presented
by ^ so many Confervoe Avhen removed from the water, and
Avhich they retain Avhen dried upon paper ; in all which particulars
they stand in marked opposition to that numerous and
Important division o f the freshAvater Confervoe, tlie Conjufateoe,
in the si)ccies of Avhich the filaments are flexible, mucous,
and shining in the highest degree: in them, too, the filaments
never taper, but are ahvays exactly cylindrical. Moreover,
the articulations differ in the tAVO groups : in the Cysto-
sperrnecs they are strongly marked, and Avhen dried, become
contracted and dark, Avhile in the Conjugateoe they are faintly
indicated ; and in dried specimens are often with difficulty
discoA’erable.
Such are the leading features o f this inte resting division
o f the Confervoe, and on a careful examination and estimation
o f the many points o f difference here enumerated be-
tAvcen them and the Conjugateoe, the tribe to Avhlch th ey m ost
closely aijproximate, there can bo no doubt, I apprehend,
o f the propriety o f retaining them in a separate family.
The differences are too great to admit of their holding
merely a generic rank. The naturalness of the different
genera forming the preceding family may be readily perceived,
these passing through certain species, the one into
the other ; and all being allied by certain resemblances :
but hoAV Avide is the interval betAveen any of these and the
group of Cgstospermeoe !
The sporangia in the different species of Cgstospermeoe are
produced in the same manner as in the non-conjugating
Zygnemata; that is, by the concentration o f the contents
of tAvo adjacent cells in the same filament, this being necessarily
always accompanied by the inflation of the receiving
cell, and the giving cell being constantly ¡daced in communication
with the narroAv end of the ovate inflated cell.
In all the Conjugateoe the endochrome is seen to pass through
tubes of connection betAveen the cells, whether in different
or in the same filaments : in these, hoAvever, no such passages
exist, the contents of the cells escaping apparently through
a rent occasioned by some agency in their extremities. The '
notice of this particular furnishes an additional distinctive
character between the T a v o groups : but others still remain,
tAvo of Avhlch may next be noticed.
The first of these relates to the presence of a peculiar and
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