F am. v i l C H Æ T O P H O R EÆ .
Char. Algæ gelatinous, ramose, composed o f principal stems
and smaller filaments, fo r the most paid ciliated. Reproduction
usually hy means o f zoospores contained in the
filaments, hut in some cases said to he capsidar.
The species of this very natural family accord Avith the
preceding in being composed of two sets of filaments, in their
extreme lubricity, and in their branches terminating in long
ciliform appendages, to which, in a measure, their great
lubricity is attributable. They differ from it, howcvei’, in
the secondary branches not being Avhorled, in the absence of
glomerules, and of the fibrillæ surrounding the primary cells,
also in being of a light and beautiful green colour, which.
In drying, does not change to some other tint, as has been
seen to be the case in the Batrachospermeæ.
The tAvo families, likcAvise, agree in habit, the Chæto-
phoreoe, lik e the Batrachospermeæ, dw elling in fresh and pure
Avater, such as that o f fountains and slow streams ; but on
account o f the delicacy o f their structure th ey are not met AvIth
in large rivers or sti’cams, the force o f Avhose current is
strong, and Avhich Avould SAveep them aAvay and destroy them.
On certain species of the genus Choetophora capsules have,
from time to time, been metAvith, but the occurrence of these
is exceedingly rare, and It cannot be supposed that the ordinary
and usual mode of reproduction is by means of these.
The true reproductive bodies in this family, as well in all
probability as in that of the Batrachospermeæ, are undoubtedly
zoospores. I f a specimen of Draparnaldia, D. glomerata
for example, be examined microscopically in its young state,
the main filaments will be seen to be quite cylindrical : at a
Later period, hoAvever, the cells, of Avhich these filaments are
composed, swell up, and the filaments then become beaded.
This inflation of the cells, Avhich occurs in almost all the
blanched Algæ, is indicative o f th e period of reproduction,
and terminates in the ru p tu re o f the individual cells, the
zoospores escaping th ro u g h th e ap ertu res th u s provided.
T h a t this is th e usual and tru e method of reproduction it is
easy to satisfy oneself in th e following method. I f a specimen
o f Draparnaldia glomerata be k ep t in water, Avhlch oug h t not
to be renewed for a day or tAvo, th e cells will be observed to
separate from each other, and, floating on th e surface of th e
fluid, will be noticed a greenish pellicle : if a portion o f this
be placed beneath th e microscope. It Avill be found to consist
o f a slimy material, in Avhich are contained numerous green
globules of very minute size ; these, if watched for a day or
two, will be seen to tak e on th e characters peculiar to the
species.
The following observations in M. Decaisne’s Memoir on
the Classification of the Algæ in the Annales des Sciences
Naturelles occur, which correspond closely Avith the views
already expressed in reference to the reproduction of the
genus Draparnaldia, and Avhich I have long entertained.
The Draparnaldia glomerata is composed, as it is known,
of a principal trunk formed by a series of large cells placed
upon each other, transparent, each occupied with a ring of
green matter, rather pale, mucous, and mixed up Avith amylaceous
globules. The branches, which arise from the points
of junction of these cells, are themselves composed of articulated
ramuli, and terminated by a confervoid ciliform thread,
which, all united, produce the mucilage AvIth which the plant
is found enveloped.
“ A t the period when it has atta in ed its complete developement,
th e hairs are seen to detach themselves successively
from th e la st jo in t : afterwards th e g reen substance enclosed
. i n each of the ramuli unites into little globules, which escape
one a fte r th e o th e r by a rounded ap e rtu re ‘ p ra tiq u é e s’ upon
each o f th e cellules. These themselves become absorbed {se '
résorbent) as soon as th e y are empty, so th a t a t a period
more advanced, one finds o f all th e p lan t b u t a single filament
enveloped Avitli mucus and filled Avith green globules.
I believe th a t I am able to conclude from these observ1
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