Additional evidence in favour of the influence exerted by
the horns consists in the fact of the capsules or seed-vessels
being cither perforated or prolonged into a short tube, ju st at
the place where it comes in contact Avith the horn. This aperture
may fairly be presumed to be intended to facilitate the admission
to the spores of the granular matter discharged by the horns.
Allusion has already been made in the Introduction to the
poAvers Avhich many Conferva possess of resisting Ioav degrees
o f temperature. The spores of the different species of
Vaucheria AAmuld appear to be endoAved with this poAver to a
remarkable extent. “ In spite of all my precautions, the
frost of Avinter reached the Avater of my vase, and my grains
became enveloped (engagées) in very thick ice. They remained
thus Aintil the period of the thaAV, that is to say, during
fifteen days, and Avhen they reappeared, I believed them at
first to be too much injured to hope for any success ; but I
called to mind very opportunely the experiments of Spallanzani
upon the different degrees of cold which seeds would
bear, Avithout losing in consequence the faculty of germination ;
and Avell convinced that the Conferva exposed to the open
air had not been more fortunate than mine, I resolved not
to abandon my observations.” The observations were continued
; and, as states the text, the grains germinated, to the
infinite delight of Vaucher.
This faculty of resisting cold is bestoAved upon the Vaucheria
and many Conferva, and especially upon their seeds,
with the evident design of guarding against the extinction of
the species, which Avould be almost certain to occur upon the
freezing Aip of the waters of the ditches in which they are
usually found. The power also which these plants, and especially
their seeds, retain of sustaining high degrees of temperature,
is scarcely less remarkable, and is doubtless imparted
to them Avith a similar provident intention. This
power in the case of the spores is to be explained by reference
to the compact capsule which surrounds them, and which
prevents the evaporation of the interior moisture. Another
precaution adopted by nature to guard still further against
the risk of the extermination of any species, is the fact
that A’ery many Conferva (the Vaucheria included), and
especially such species as inhabit shallow and extended waters,
mature and shed their seeds prior to their drying up, and that
the special period of their doing this varies in a measure with
that of the exhaustion of the water.
F u rth e r research will doubtless disclose many other species
in addition to those described to be inhabitants of the
fresh waters of Great Britain. Few species of the genus
Vaucheria dwell in the sea. They bear, however, a close
analogy to the marine genera Bryopsis, Codium, and especially
Ectocarpus. M. Deeaisne places the Vaucheria in his class
Aplosporea, a class in which the Batrachospermea find a place.
They are much more nearly related to his Sunspores, than
to the family of Batrachosperms.
a. Vesicles lateral, solitary.
1. V aucheria dichotoma Ag.*
Plate IV. Fig. 1.
Char. “ Frond setaceous, dichotomous, fastigiate. Vesicles
solitary, globose, sessile.”— Grev.
Hooker’s Brit. Flor. vol. ii. p. 319.; Conf. dichotoma, E nglish
Botany, t. 932.; Harvey’s Manual of British Algaa,
p. 147.; Berkeley’s Gleanings; Dillwyn’s British Con-
fervse, t. 65.
Hah. “ In ponds and ditches; fre q u en t; an n u a l; spring
and summer.”
“ Fronds setaceous, a foot or more in length, dichoto-
mously branched, forming Avide strata at the bottom of pools,
and frequently filling th em ; colour, a pale yellowish green,
and occasionally dark.”— Harv. I much doubt whether this
is anything more than a condition of Vaucheria sessilis, the
capsule being of precisely the same form as in that species, and
upon undoubted specimens of which it is by no means uncommon
to find solitary capsules. A yelloAvish or olive green is the
colour of all the species of the genus Avhen aged and in seed.
* The abbreviation of the name of the individual affixed to the specific
denomination of any production does not necessarily imply more than tlie
fact, that the person thus alluded to was the first to place that production
in the genus Avith which it is in this work described.
E 2