The Vegetable World: Being a History of Plants, with Their Botanical Descriptions and Peculiar Properties

Here we are permitted to behold a very astonishing phenomenon. Are these young beings really plant#? The German botanists call them Zoospores. They identify them with animals, remarking that animals only have organs of locomotion, and that the vibratile cilia which are observed in the spores of the Vaucheria are true organs of motion. Thus, according to certain German naturalists, at the commencement of their lives these Fuci are true animals, which only become f plants when they are fixed and begin to germinate.

Apart from this theory of transformation, Unger’s remarks upon the clubbed Vaucheria, V. Clavata, are highly interesting. While examining this plant he found that the vesicular summits had Fig. 308. Young the power of contraction, Vaucheria. and that by this process they expelled the contained sporules,which, after expulsion, ascended to the surface of the water. H ppening to look at the surface of this water, he was surprised to find it covered with small globules of unequal size, swimming freely here and there, and gliding round glo-bulesthatremained motionless, st PI i g d g in setti gth | it motion, like animated beings. The next day a great number of these globules aggregated round the bubbles of gas disengaged from the Conferve, and floated at the surface,—some dark green, others round or elongated, others transparent, humid, diverging at Tight angles with each other, all evidently plants in a state of ger- Mination. Other globules were oval, dark at one extremity, and almost ‘Transparent at the other, which swam freely about, and ene the Space of an hour he succeeded in tracing not only the diminution of vitality and the death of these infusoria, but the subse- {ent development of the dead animals into germinating plants. Pg French botanists are more cautious in expressing their

"Ws; they dare not pronounce upon the animality of these thent and the researches of M. Decaisne prove beyond a doubt Pe aaa nature of the so-called zoospores, a doctrine to which = aia eminent English philologists had long given their a For ourselves, we confine ourselves to this brief expla-of both opinions, en the spore has become fixed, it develops itself regularly;

its progress is easily followed under the microscope. The elongation of the filaments take# place, so to speak, under the eye. M. Thuret states that he has measured more than once an increase of three-twentieths of a millimetre (about three-eightieths of an inch) in an hour. Besides these non-sexual multiplications by zoospores, there has been recently discovered in the same plant a true sexual reproduction, produced by the assistance of two distinct organs, borne at a little distance the one from the other on the filaments. The one B (Fig. 309, a) is a sort of short branch, re-curving as it were upon itself, like a snail, or small horn. The other, 8, is a sort of shell, light and thin, an Ssss= fashioned like a beak, which is ca

Gg22soe S22" the sporange. These two organs are separated, the one from the other, upo®

Fig. 309. Sporangia of the Vaucheria '2€ tube which carries them, by: Sint Peon getion: transverse chamber. In the interior© the sporange, and towards its base, certain green seeds are found, while towards the beak is a colourless matter, very finely granulated. At the extremity of the cornicule, which is bounded by a thin partition, a great number of small clubs are

| SESS found, more or less surrounded by a colour-

4 less mucilage. ‘ Such is the state of things when fecunda-

Fig. 310, Antheromoia tion takes place. At this moment he of theVaucheria. of the sporange is broken at its tip, and t matter contained in this species of sac is poured out through the opening (Fig. 310). Immediatety after the sporange opens; the cornicle, by a marvellous coincidence, opens also at ey extremity, and pours out its contents. Innumerab e wolt Wo},Ae! corpuscles of minute size, but retaining their club-: like shape, that -is to say, antherozoids, now ee from the cornicles. They penetrate the — opening of the sporange (Fig. 311), filling 1¢ a

Fig. 311. Anthero- entirely. Arrived at the surface of the mucous zoids penetrating the Sporangia. anulous bed, which prevents them,by its pare | from penetrating further, they advance and retire, continuing "™"

backward and forward motion during the next half hour, presenting 8 most singular spectacle to the observer. Sometimes a partition is formed in advance of the mucous bed, which prevents the ulterior action of the locomotive corpuscles from exercising themselves upon it. These movements will endure for yet another hour; but they become gradually slower and slower, ceasing entirely at the end of a few hours. It is after the introduction of the antherozoids into the sporange that a large cell or spore forms itself in the interior of the sporange, which completely fills it. At first greenish, oS this cellule becomes paler by degrees, and A presents in its interior many larger bodies of a sober brown (Fig. 312). Sometimes it is isolated from the tube in consequence of the membrane of the sporange beginning to decompose. At a certain time, that is, in about three months, this spore begins torecover its green colour; it becomes "is: #12-_ Formation of Spores. elongated slowly, and soon assumes the form of a young tube of Vaucheria, and in a short time it is a perfect resemblance of the mother plant (Figs. 313 and 314).

Figs. 313, 314. Spores of Vaucheria germinating.

ae is the double and singular mode of fecundation in the @ucheria, It was foreseen by.Vaucher, who recognised the utst, and suspected the importance of the cornicles; but we are indebted to Von Pringsheim, an able German anatomist, for the “omplete and circumstantial relation which is here presented. The ny vesiculosus (see Fig. 315) is the commonest and best known of _ @ the Marine Algz. It is found on all the shores of Europe, and

in the North Sea it grows so abundantly that it is used for domestic purposes, such as roofing houses. It is also cut twice a year in some places in order to extract soda from its ashes after burning it. The plane part of its bifurcated frond is sown with

Fig, 315. Fucus Vesiculosus,

ine ee probably which are air-bags, vesicles orglobulous sustain the plant in the water and perform the functions © air-cells in fishes. Certain mamelous tubercles invest the © tremity of the bifurcations of the frond. Jant

If the water is withdrawn from certain portions of the P re at the time when the tubercles are fully developed, 1 38 se. times observed that their orifice is closed by a drop of Be liquid, while other portions of the same plant present m circumstances a sort of secretion, no longer red, but olive. vice

This change of colour seems at first glance to indicate a P a

logical difference in the tubercles borne upon the different fronds. The fact seems to be that each of these tubercles is only a cavity or conceptacle, enclosing in the one case a fecundating apparatus, in the other a fruit-bearing organ; and these organs are borne upon separate tubercles. /ucus vesiculosus may therefore be considered as dieceous. “The fructification of the Fucacex,” says M. Thuret, “is contained in small spherical cavities situated beneath the epiderm, called conceptacles. These are completely closed at irst, but open eventually; they open at the surface of the frond y @ small pore or mouth, through which the reproductive bodies eseape, assisted by jointed and branched hairs or cilia, which line the conceptacle which supports the antheroids, and it is at their base that the spores are fixed. In certain species, spores and

Fig. 316.—Transverse section of the Conceptacle.

antheroids are found in the same conceptacle; in others, on the contrary, these organs are produced in different conceptacles, and on different individuals.” alas male conceptacle of F. vesiculosus (Fig. 816) is found to : small ovoid, transparent sacs, containing a whitish mass These are the antheroids whichemg with reddish granules. hairs reticulated upon the branched or supportedag ae ne the conceptacle. They enclose numerous transparent but in time the "Puscles, at first yery thin and colourless, R

matter condenses into little bodies forming a greyish mass, sprinkled with orange or reddish spots. These corpuscles are the antherozoids, which are so packed that neither form nor structure can “ be recognised. The antherids of Fucus, Ozothallia, Pelvetia, and Himanthalia have a double envelope; that is, the sac in which they are contained is itself closed by another of the same description, which remains fixed to the hair on which it was produced, while the inner one is expelled through its summit and falls mto the conceptacle, whence it glides as far as the mouth. The antherozoids which fill it soon become violently agitated; the sac opens at one or both ends, through which they force their way ito the and Cystoseira,stamen and disperse. In Halidrys, Pyenophycus, the second envelope is absent, the mere sac only is found attached to the jointed hairs, and the antherozoids are expelled directly and in a mass, remaining fora time in ceaseless struggling, and turning upon one another before dispersing in the liquid, where they move with great vivacity. Their locomotive organs consist of two cilia, the shorter of which appears to be inserted at greatly attenuated, the smallest extremity of the body, which is always in advance during its progress. The second cil is drawn behind the corpuscle.

In what some botanists designate the female conceptacle of Fucus vesiculosus (Fig. 317), certain membraneous sacs, more OF Jess spherical or ovoid, are found, enclosing a rounded opaque mass, of a greyish brown, divided into eight parts. These sacs or sporanges 87 borne upon a short peduncle, and surrounded by articulated a? ments. When the sporange opens, as the antherozoid does a? a given monrent, the mass which it contains is set at liberty, i preserving its original form, so long as the inner sac is suffice ge strong to restrain it. But matters do not remain long 1? ©: state; the spores isolate themselves more and more in the mem braneous envelope which confines them, and finally they i free. They are then perfectly round, of an olive yellow, 2” absolutely destitute of skin.:

M. Thuret, to whom we are indebted for some excellent _— vations on the structure of these vegetables, has established pees experiments what becomes of the spores when disengaged their envelope. “If the male fronds, which are easily recogms®

by the yellowish colour of their receptacles,” he says, “ are placed for a short time in a humid atmosphere, an effect is produced analogous to what has been described in the female. The antherids, expelled in immense quantities from the conceptacles, form on the surface of the frond at each ostiole, or mouth, small viscous mammals of an orange colour. When a portion of the viscous matter is detached with a needle’s point, and examined wit