i n I ' ! [
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extract of opium are very remarkable : tbc motion is retarded
gradually, so tliat the play of these organs c.an be well distinguished.
The iodine water, although it contains hut an
extremely small quantity of iodine arrests suddenly
the cilia, which become plainly visible. The alcoholic
tincture of iodine may also be employed, but very Aveak. I f
afterAvards the spore is dried betAveen tAVO plates of glass, the
cilia Avill be sufficiently distinct to be seen by the simple
microscope.
M. Unger has folloAved the movements of a liberated spore
in Avater during more than tAvo hours. The greatest length
of time during which I have observed it Avith the microscope
has been nineteen minutes, and, in general, the motion continues
but little more than half of this tim e : sometimes it ceases
almost immediately after the release. B u t it is necessary to
remark, that the spore, being placed upon the object glass,
was imprisoned between two plates of glass. The vibration
of the cilia continues sometimes after the spore is arrested ;
only It is not sufficiently strong to displace the corpuscle.
Wlien at last they cease to move, the contour of the spore
undergoes during some instants a sensible alteration, which
announces, perhaps, the decomposition or the absorption of
the vlbratile organs. The motionless spore delays not to
modify itself once ag a in : it becomes spherical, the green
matter distributes itself equally, and the episporic membrane,
In part reabsorbed, at last escapes the s ig h t; very soon germination
commences.
M. Unger remarks tha t the escape of almost all the spores
takes place toAvards eight in the morning. Indeed, all the
work of the formation of the spore is carried on in the first
liours of the day. The tufts Avhich I have gathered the day
before, and which presented no indication of the formation
being near at hand, were in general covered with spores
tlie next morning; and after mid-day these were all gathered
on tlie surface of the water beginning to germinate.
I t is easy to follow the progress of this germination under
the microscope: the elongation of the filaments progresses,
one might say, by eyesight; for I have measured more than
once an increase of three-tAventlcths of a millemetre in an
hour. Moreover, the activity of tliis phenomenon, as of all
those Avhich I shall hereafter describe, varies extremely,
according to the state o f tlie tufts o f Vaucheria which have
been gathered. I t is the same with the diameter of the spores,
and the size of the filaments, &c., upon Avhich one is not able to
give a certain determination. Therefore, in the figures which
I append to this note, all the modifications which the spores
of Vaucheria may present, either before or after their emission,
ought not to be expected to be found; but I have
chosen in my draAvings those which have appeared to me to
represent their most usual and characteristic state.
The poAver of germination is moreover carried in Vaucheria
to a point Avhlch appears to me to surpass all that is observed
in the vegetable kingdom. This plant, Avhlch consists, to
speak truly, but of a single cell, possesses in all its parts the
faculty of reproducing itself. The extremities of the filaments
kept for many Avecks, evaporation being prevented,
continue to elongate until they have extended themselves
beyond the plate o f glass which serves to sustain
them. Again, Avhen one of these filaments has undergone
lesions in many places, the green matter is seen to become
secreted gradually between one end of the injured places and
the filament, and to divide itself thus into many little
fragments, Avhich form so many distinct individuals emitting
lateral prolongations, and not tarrying, Avithout doubt, under
favourable circumstances, to reproduce a complete individual.
The phenomenon of the deliverance of the spore is not ahvays
accomplished so regularly as I have described; sometimes it
germinates without quitting the mother p la n t; and from this
result the strange forms which I have represented in figures
35 .and 36. Sometimes also the spore cuts itself into two
at the moment of its escape, and so gives birth to tAvo spores,
smaller than the others, but capable of germination like
them, the one at the exterior, the other at the interior, of the
filament.
The transparent membrane Avhich enclosed the spore, and
A v lu c h became visible after its emission, is destroyed little
c 2