tlioêc cells, even îii the young cand but little dcA^clopcd Vesi-
vulifera, which .arc destined to c.arry the true spores when
the sjiccics shall havæ arrived at the ijerfccllon of its life.”
IMcycn, by Avhoni this interesting structure seems first to
have been noticed, gives the following account of its characters
111 a sjiecics which he calls Conferva rivularis : —
“ The annular structure aplicara worthy of notice, which
the upper end of many of the joints of the Conferva represented
exhibits. This appearance is altogether analogous to
■the annular structure observed in the horny coat of the
Campanularioe. In those polyjii also this structure appears
first at an advanced period of growth, as is the ease with
the Conferva, and indeed in very diflcrcnt species of articulated
plants of this family. The formation commences with
a thickening of the membrane ; the constrictions, then .appear,
which arc not spiral, but run in horizontal rings one
above the other. Sometimes it seems as if this ringed substance
were an entirely new formation.” — Meyen, PJlan-
zen-physioloyie, vol. iii. p. 451.
The above is the entire of Meycn’s account of this corrugated
formation, which docs not in all resjiects accord with
my own observations. The structure is, amongst freshwater
Alg.03, confined to the species of the genus Vesiculfera.
“ The purpose to which the annular disposition of the horny
coat, of not merely the Campanularioe but of most hydroid
Zoophytes, is subservient, is probably that of rendering their
Iioly^iidoms more flexible, and consequently less liable to
injury from the agitation of the restless element in which
they dAvell.” *
The second particular refers to the central cytoblast or re-
].)roductivc vesicle, which, in the group of Cystospermeoe, is
•circular, whilst in one genus of the Conjugateoe, Zygnema, it
■is somewh.at quadrlform, and furnished with tubular offsets.
I t is at once .apparent, that the mode of reproduction just
indicated, does not differ essentially from that first made
known hy Vaucher, with reference to the Conjugateoe, and
*■ See Aiinals oI'NuL Hist.
especially in fcspcct to those most interesting species which
1 liavc described as producing true s])orangia, without union
of the filaments.
Tills discovery of the identity of the mode of reproduction
of the two families of Confervoe hitherto treated of, leads
necessarily to some general, and not unimportant conclusions.
Thus, it furnishes satisfactory evidence of the intimate
and general connection whieh exists between these two
families, which include such a considerable proportion of the
freshwater Confervoe, whereby much light is thrown upon
the often canvassed and much disputed subject of the animality
of the conjugating genera, for it proves, since in
•reality a conjugation takes place for the formation of all
true sporangia, that both stand ujion the same footing as
regards their animal natm’c, a fact, which hitherto has never
been suspected, the vegetable character of the Cgstospermeoe
having long been considered as estabiishcd, and that if those
species which exhibit the curious phenomenon of conjugation
arc really animal, so are all the true Confervoe ; thus, if these
should at any subsequent period he removed from the vegetable
kingdom to the animal, so ought, as an inevitable consequence,
all the other Confervoe which I have included in
the group of Cystospermeoe.
B u t it appears to me that, from the fact disclosed of the
union and concentration of the contents of two cells in so many
Confervoe, no argument can be deduced cither in favour of
the sexuality or animality of the Corfervæ, numerous species
occurring, as already observed in the Introduction, In which
this curious phenomenon is wholly wanting.
For my own part, I trouble myself but little with the
disputes about the boundaries of the two great divisions of
the organised world, which forcibly remind me of the search
carried on by ancient philosophers, for days and years, after
the much-desired, but imaginary philosopher’s stone, endowed
with such all-pervading influence, or the equally fruitless inquiry
after perpetual motion, or .any other of the Avild chimeras
to w h ich .the minds of men have from time to time been
given. I t is my belief, that no such rigid boundary exists ;