Draparnaucl, and tha t skilful naturalist approved of it.
lloth, and after him Vaucher and Decandolle, have adopted it,
Avith the trivial name of Weiss, Avhich has become general.”
T h e Batrachosqterms are highly flexible and mucous to th e
touch, th e ir lu b ric ity arising in a measure from th e presence
o f innumerable lashes or cilia, termin atin g th e branches,
Avhich add also infinitely to th e microscopic b e au ty of these
productions. V aucher en te rta in ed th e idea th a t th ey Avere to
be regarded as th e stamina o f th e plant, and th a t th e y were
filled Avith a fecundating powder. This opinion would
appear to be mere conjecture, th e only fact in support of
it being th e deciduous character of th e organs. E a ch
cilinm is articulated in a manner similar to th a t o f th e
branches, of Avhich th ey may be regarded as extensions.
The species of this genus in h ab it mostly p u re and ru n ning
Avaters, being usually met Avith in fountains, Avells, and
streams, th e force of which is no t considerable. T h ey are
so exceedingly flexible, th a t th e y obey th e slightest motion
o f the fluid Avhicli surrounds them, and Avould seem almost
to be endoAved Avith v ita lity ; nothing can surpass th e ease
and grace of th e ir movements. W h en removed from th e
Avater th ey lose all form, and appear h k e pieces o f je lly ,
Avithout trace o f organization, on immersion hoAvever th e
branches again quickly resume th e ir former disposition. They
adhere strongly to paper, and in drying freq u en tly change
to some other tin t, usually much deeper ; on being moistened
afte r long intervals, th e y recover much of th e ir original
freshness ; and it is even asserted th a t, a fte r having lain
in tlie herbarium for some years, when th e y are replaced in
water in a suitable locality, th a t th e y will vegeta te as before.
T h e manner in Avhich th e glomerules are developed does
n o t seem to be well understood * ; each would appear to he
compounded o f numerous cells, all having a single and
common atta chmen t to th e p a ren t p lan t b y means of a single
and slender th re ad ; from Avhich th ey , Avhen mature, separate,
* In the earliest period of their development they Avould appear to be
minute excrescences growing out of the walls of the cells, from which
finally they become entirely separated in most of the species of the genus,
hut not in all, as in B . atrum.
or are thrown oflF. They would appear to partake more of the
nature of buds than seeds. When developing, each emits
numerous branches, which radiate in all directions.
Bory would seem to be the only observer who has studied
the species of this genus with that nice discrimination which
they require : in associating Batrachospermum atrum, however,
and some other species with the genus Thorea, he has
committed a great error. By a careful comparison of specimens
derived from the herbarium of Dillenius, which are
in the collection of M. de Jussieu, with others collected by
Roth, Mertens, and Draparnaud, Bory has succeeded in
ascertaining the correct synonymes of several species or varieties,
Avhich had previously been quoted indiscriminately.
From the great number of specimens described in the
following pages, there are some, I fear, who will be disposed
to think th a t they have been multiplied on insufficient
grounds: such an opinion I am sure Avill not he
entertained by those who have carefully studied the genus
for themselves, and who have had opportunities, as mainly
through the liberality of friends I have had, of comparing
a considerable number of specimens collected from widely
different localities together.
I suspect tha t the species of this genus are propagated
not merely by gemmæ or glomerules, but also hy Zoospores,
contained as in other Algæ zoosporæ in the cells, of the
aggregation of which these plants are composed.
The affinities of the genus are by no means direct, in their
lubricity, in the presence of cilia, and probably in their
reproduction by zoospores they bear a certain relationship
to the family Chætophoreæ.
a. Filaments exceedingly flexible.
1. B a t r a c h o s p e r m u m b o m b u s in u m Bory.
Plate X I I I . Fig. 3.
Char. Frond delicate, filaments sparingly branched, branches
simple. Cells much elongated. Verticilli minute, distant.
H 4