The organization the most simple, is that which is found
in the Conferva; and I have reason to think tliat it represents
a type general to the spores of the Alga. I have
studied it in the Conferva glomerata and C. rivularis ; the
spores are altogether alike in both species, and I have seen
in the one all that I have observed in the other. Their
form is turbinated; the thin extremity, deprived of endochrome,
to which the name of rostrum or beak has been
given, bears two cilia or filiform tentacles, the length of
Avhich surpasses tha t of the spores ; they are the locomotive
organs. (See Plate I. 1, 2.) The spore moves ordinarily
with the beak in advance, and turns about in the water with
a movement of trepidation, which recalls to mind tha t which
I have observed in the animalcules of the anther of Chara :
this analogy applies Itself more closely from the resemblance
of the organs of locomotion. From time to time the spore
suddenly stops ; and often, likewise, it twirls round upon its
great axis. The light exerts a marked influence upon the
direction of its march. A small quantity of the watery
extract of opium is sufficient to arrest their movements.
The tentacles are then easily distinguished by a linear power
of 240 times (la vue moyenne étant comptée à 25 centimetres).
They are rendered still more visible by employing
the alcoholic tincture of iodine, inore or less Aveak. I f after-
Avards the spores are left to dry betAveen tAVO plates of glass,
the tentacles Avill not be observed to he altered by the
drying, but they come in a manner more satisfactory and
poslti\’C upon the bottom of the microscope, because they
are placed in a medium less refracting. I t is necessary to
remark, moreover, (and this observation applies to all spores
of the Alga Avhlch are prepared in this manner,) that, the
spore contracting itself by drying, the tentacles appear a
little longer.
I t is in the morning more particularly th a t the greatest
number of spores of Conferva are found in action. Those
which one observes after mid-day are for the most part
stopped, or have already commenced to germinate. The motionless
spores all present, tOAvards the beak, a point coloured
red, which adds still further to their resemblance to certain
Infusoria, especially to some Thecamonadiens.
The Chatophora elegans (var. pisiformis) presents to us
a more complicated organization. The beak bcarg four locomotive
tentacles, instead of tAVO. These spores are very small
also, and difficult to observe. (See P la te l . f g . 10.)
In th eP ro lfe ra (Conferva vesicata, tumidula,axià alternata'),
the organization is still more complicated ; and this difference
of the spores is an additional motive for separating these plants
from the real Conferva. T aa^ species of this kind have served
me in my researches : the first seems to be referrihle to Prolifera
rividaris of M. Leon Le Clerc* ; and the other, a great
deal smaller in all its parts, to Prolifera Candollii of the same
author. Both have the spores, the beak is rounded, and bears
a croAvn of filiform tentacles (see Plate V f g . 13. 18.), which
opium or iodine renders motionless. Their movements are
very nearly the same as those of the spores of the Conferva,
but much more rapid, by reason of the greater poAvers of their
locomotive organs. Yv'hen these spores are disposed to germinate,
they fix themselves by the beak to all tendrils which
float in the Avater, and throw out prolongations or root-like
claAvs, Avhich render them very adherent. The filaments of
Prolifera, or Conferva, are often rendered rough Avith this
kind of parasitic vegetation. This fact, ill understood, caused
the creation, by Vaucher, of the erroneous appellation of Prolifera.
I f the plant is removed from the Avater at the
moment of the emission of the spores, they fix themselA’cs
around the crystals produced by the evaporation of the liquid ;
and when the germination commences, one may see eveiy
little crystal charged Avith a multitude of spores AAdiich
radiate in all directions.
The Vaucheria, estranged from the genera of Avhich we
have been speaking, by its structure, and by the mode of the
formation of its spores, is distinguished equally by the disposition
of its locomotive organs. The spore is an ovoid
* Sur la Fructification du Genre Prolifère. (Mémoires du Museum,
tom. iii. p. 462, pi. 23.)
i