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F.Jsay on the Irritability of the Sexual Organ: of Plants,

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ing, is not an attribute peculiar to them. A great number of plants exhibit signs of irritability more or less apparent in proportion to their age, their strength, or the part to which the irritating cause is applied. Several authors have observed thi3 in the leaves and flowers of many plants. M. Dunamel has accurately described the curious motion of the sensitive plant. M. Eonnet has proved that leaves possess the power of voluntary motion, that they always present their upper surface to the air, ?nd that whenever a branch Is turned out of its natural position, the leaves of it immediately assume a new direction. Linnæus has carried his inquirius on this subject dill farther, and, in a dissertation, intitled Somrnts Plantjrum, has demonstrated the daily motion of the leaves in a very considerable number of plants, and has proved that the phenomenon does not depend on the state of the atmosphere. After having observed that many flow

vegetable life. They can no more be accounted for by mechanical laws than the muscular action of animals; fof both undoubtedly depend on the fame causes, which we shall never be able to discover.

•The motions that take place in the stamina and pistilla have hitherto been observed but in few plants, such as the barberry (berberis vulgaris,) the Indian fig (cafrni opttntia), the 'dwarf cistus (ciflus helianthemum), and some others, which are enumerated in one of the dissertations of the /Imanitatcs Academicœ, intitled Spin/alia Plantarum. These organs, however, display an irritability more universal and more manifest than is to be found in any other part of the plant. We (hall presently establish this fact by a detail of observations made on the sexual organs of a great number of plants.

Motions of the staminas.

The antheras of several species of lilies before the capsules open are fix

ers open pretty constantly at stated *ed lengthways on the filaments, and hours of the day, he very ingeniously parallel to the style, from which they

conceived the idea of making these flowers answer the purpose of a clock, under the title of horologium flora. It is known that the extremity of the leaves in the diontea muscipula open with two valves, like a trap, and suddenly close upon the least irritation. The leaves of the hedysarum gyrans *, or moving plant, likewise exhibit the most evident and wonderful motions. These different movements of the leaves and of the petals, as well as those of the stamina and pistilla, which we are about to describe, seem to us to depend essentially on the particular organization of the plants, and on their

are distant about five or six lines. When the pollen begins to issue from its cells, the antherse become moveable on the extremity of the filament* that sustain them, they approach the stigma one after another, and retire again as soon as they have shed their dust on that organ. These motions are very evident in the Canadian martagon (lilium fuperbum.)

The stamina of the Jacobæa lilly (amaryllis fonnojiffima), those of the fea-dassodils (pancratium maritimum y illyricum), exhibit a very curious phenomenon, and somewhat different from that just mentioned. The an

ther*

* Vide F.din. Mag. for September I7S7, p- 160.

f Perhaps it may be necessary, for the sake of some readers, to explain the terms here made use of. In the centre of most flowers, there Hands at least one body called the Pillillum, or Female-organ, which consists <rf three parts; the undermost is the germen, that in the middle is the style, and the uppermost, or top, is the stigma. Round it stand several other bodies, called Stamina, or Male-organs, each consisting of two parts j the undermost is a thread-like substance called a filament, sustaining the anthera. This last generally consists of two cells or capsules, which contain a powder called Pollen, or Farina.

EJsay en the Irritability as the Sexual Organs ofPhtntu

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therx of these plants before fecundation are like those of the lilies fixed along their filaments parallel to the style. When the cells begin to open, they assume a horizontal position, and sometimes turn on the extremity of the filament, as on a pivot, that they may apply to the stigma the particular part by which the pollen is escaping.

If we observe with attention the stamina of the Persian sritillary (fritillaria perjica), we will discover an irritability still more obvious. The six stamina of this plant are four or five lines distant from the style before fecundation; but almost immediately after the flower expands they successively approach the style, and apply their anthene close to the stigma. Aster the pollen is discharged, they recede generally in the same order as they advanced, and ti.ke their former distant station. These motions are sometimes performed within the space of sour-and-twenty hours. Similar phenomena are obsei veable in the stamina of the floweiing rush (butomus umbellatus), and even in those cf many species of allium, ornitkogalum and asparagus, but in these indeed they are not so apparent.

I have never observed any motion in the stamina os the crown imperial (fritillaria impirialis ), or in the fritillaria meleagr/s; but these two plants at their fecundation present a phenomenon of another kind not less interesting. Their stamina stand naturally close to the style, and the stigmata surpass them in length. Any particular motion, therefore, bestowed on the stamina of these plants, could have answered no purpose, and accoidingly nature has made use os another means to assist the process of fecundation. Their flowers are made to hang down while the pollen is discharged from its cells, that it may the more easily fall upon the stigma and fertilise it. What renders this explanation probable is, that as soon as the fecundation is performed, the footstalk of the flower be

comes erect, and the germen is sustained in a vertical position. The same circumstances take place in the columbines (aquilegia), in the different species of campanula, and in many others which are mentioned by Linnæus.

But the plants of this particular class (the URacex), are not the only ones that shew signs cf irritability; such are observeable in many others of very different natural families. The rues (ruta) present us at once with a very striking and obvious example of this faculty. All the plants of the genus have from eight to ten stamina, of which one stamen is opposite to each petal, and one stands in the interstice between every two petals. If the stamina are observed before the discharge of the pollen takes place, they are found at right angles with the pistillum, one stamen lying in the cavity of each petal. When the moment of fructification arrives, they raise themselves up two and two, or three and three together, lay their antl.eræ upon the stigma, and, after having fertilized it, they retire and fall back again into the cavity of the petals. I have likewise remarked very evident motion in the stamina of the xygcphyllum fabagt. These proceed, one after another, out of the corolla, and present their antheræ to the stigma. The stamina of the sraxinella (ditlamnxu albus), a genus approaching very nearly to that of the rue, affords a very curious spectacle which is favourable to our opinion. Before fecundation the filaments are inclined downwards, so that they almost touch the lower petals. As soon as the capsules are ready to open, and the action of the pistillum irritates the stamina, their filaments, oce after another, bend themselves io the form of an arch towards the style ; by which means the antherac are placed immediately above the stigma, so that the pollen must fall on that organ and fertilize it.

If we observe the stamina of the Indian cress (tropxolum), when the cells are about to burst, we will easily perceive that the extremity of each filament forms a curve, and bears its anthera towards the style. This approach indeed is much less quick and less sensible than in the fraxinella. Lastly, the geranium fuscurn, g. alpinism, and g. reflexum, afford similar observations. Their stamina, before the antheras open, are all bent so that their top is turned to the centre of the corolla. When the capsules begin to open, the filaments rife towards the style, and each of them generally touches its corresponding stigma. Those of the columbines raise themselves nearly in the fame manner a little after the unfolding of the flower.

Essay on the Irritability os the Sexual Organs (f Plants.

To what cause are these motions to be attributed but to the action of the pistillum, which irritates in each stamen a peculiar organ somewhat similar to that of animals? Indeed, if these motions do not depend on irritability, vhy should the stamina approach the style only at the instant when the antheræ are about to open ; and why should they recede from it immediately aster they have shed their pollen on the stigma? I shall here bring a few other facts to prove that the motions of the sexual parts of plants do not depend on a mechanical cause. Let us begin with the saxifrages. Immediately upon the opening of the corolla, the ten stamina of the greater part of these plants are some lines distant from the style: they approach it afterwards generally by pairs, and recede in the fame order afeer the pollen is discharged. The stamina in many plants of the natural older of caryophyllei, and, among others, those of the Jiellaria, of the chickweed [alJine media'), and of the mœrrhingia vsuscosa, betray a very evident motion towaids the pistillum. Those ofthe/>7lygouum tataricum, p. pensylvanicum, and the greater part of that numerous genus, exhibit motions very similar to those of the saxifrages :. differing only

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in this, that the stamina of the polygonums generally approach the style by turns. I have observed the fame contraction in those of the fwertia peremits. The stamina of the grafs of Parnassus {parnafsia paluftris), raise themselves very quickly, their filaments are so bent that each anthera is laid immediately over the stigmata, and as* ter having performed the office of fecundation, they retire and hang down towards the ground.

If we attend to the flower of the little field-madder (Jherardia arvenJis), immediately after it is expanded, we will likewise perceive that its four stamina go by turns to disperse their pollen upon the stigma, and that they not only recede after a few days, but that they sink down while they describe the semi-circumference of a circle. Those of several species of veronica evidently approach the centre of the corolla immediately above the. style, so that the pollen may fall perpendicularly upon the stigma. This may be easily observed in the veronica arvensts and v. agreftis. The filaments of the several species oPvaleriana stand erect and close to the style during the discharge of the pollen as soon as it proceeds from the capsules, and then bend backwards, as in the Jherard'ut. Those of the rhamnus palyurus also bend back in the fame manner, after the fecundation.

Let us next attend to the stamina' of the katmia. These are ten in each flower, which are kept in a horizontal situation by means of an equal number of cavities round the middle of the corolla, in which the top of each anthera is lodged. When the capsules are about to open, the filaments make a curve that the antheise may overcome the obstacle which confines them, and may be at liberty to scattet their pollen on the stigraa.

The stamina cf all those plants, which we have hitherto mentioned, approach the style by turns, sometimes by twos or by thiees; those of the tobacco 334

Ejsay on tht IrritahiUty tsthe Sexual Organs es Plants.

Lacco [tikot'uina tabacum) often go all ac once to fertilize the pistillum, and touch it so closely that they seem to form a crown upon it. They fall back again immediately aster the process of fecundation is compleated. Those of the delphinium and garidella afford a remarkable peculiarity. Before, and at the time of fecundation, all the (lamina are bent and applied close to the style; they afterwards stretch themselves out, and remove from the piftillum in proportion as thefpollcn escapes.

The two short stamina of the Jiachys have also an evident motion, which seems to have some analogy with that of the delphinium. Before the anthene open, they are contained in the cavity of the superior lip of the corolla, and placed laterally against the style. Immediately after the discharge of the pollen, they separate, the one towards the right, the other towards the left, in such manner as that the extremity of the filament is exserted beyond the sides of the flower. This divergence of the stamina is so obvious and so constant, that Linnæus has established the generic character of the Jlachys on this circumstance, which docs not take place till the ]>ollen is shed. The fame phenomenon is observable in some species of Leonurus.

The motion of the stamina in the asarum must not be passed over. Each flower has twelve stamina, and the style is a cylinder crowned with fix stigmata. When the corolla is just expanded, the filaments are folded double, so that the top of each anthcra rests on the receptacle of the flower. When the time destined for fecundation is come, these filaments raise themselves upright, two and two together; thus the antheix become vertical, and each pair goes to touch its corresponding stigma.

Lastly, the stamina of the Jcrophularia shew manifest signs of ii ritability. All the flowers of this genus have sour stamina, the filaments of which besore fecundation are ceiled up like a rib

band in the infide of the corolla: btrf when the pollen is ripe they unfold, stretch themselves out one after another, and Carry their anthers to the stigma.

We are the more inclined to consider these motions as irritability, be cause in some individuals, such as the barberry, the Indian fig, and mull of the species of cistus, they may be accelerated at pleasure by irritating tha stamina with the point of a pin.

We mall not deny, however, that there are motions in the stamina of certain plants, that seem evidently to depend on mechanical action. Such as those which have been observed in the parietaria, and ia the fcrjkobltj, the cause os which is well known. A very sensible and quick motion has also been observed in those of the mul* berry and nettle, which I do not consider as the effect of irritation. Their filaments are bent like an arch, and kept in that position by means of the foliola of the calyx which compresses them laterally. If we widen ever so little these foliola, or if we gently raise the stamina with the point of a pin, they suddenly start up and discharge to some distance a quantity of pollen. But this is not the case with those motions which we have supposed to depend on a stimulating cause: in them the stamina are entirely free from any obstacle, and the contraction is so obvious and so constant, that it h hatdly possible to deny it to be the effect of irritability.

This faculty, it is true, does not appear in every plant: those in particular in which the stamina are placed very near the style and the stigma, have never (hewn the least signs ot irritability: such are the compound flowers, the labiated, the personated, and the papilionaceous: such are the different species of verherta, vitt&t phlox, primula, and borage. Neither have I ever observed any other than elastic motions in the plants of the dioicous and mcooicous clisics».f*d

EJsay on the Irritalillty os the Sexual Organs of Plants. 33$

even these are rare. In (hort, the sta- The three stigmata of the tulip (/«

mina of many hermaphrodite plants, lipa grsneriana) are much dilated be

although naturally situated at a dis- fore fecundation, but visibly shrink af

tar.ee from the style, shew no symp- ter having received the pollen. Lin

toms of motion. In this number are næus has made the fame remark on

(he cruciform plants, with the several sjiecies of p.tonla, papaver, ranuncuhi, hypericum, Sec.

Mitiou os the parti of the Plstillum. The motions of these parts are less universal, and, in general, less appa

the gratiola. Gratiola, fays he, vjlro venerto agitata, piflilktm Jligniate hiat, nil nisi masculinum pulverem affeilanj, atsatiata riflum claudit. Hort. cliff.o. The different motions in the several organs of plants, of which we have

rent than those of the stamina, as if here related so many striking examine law which determines the males Ples» scem "> "" a function dependent

of most animals to go in quest of the females were extended to the vegetable kingdom.

We may, however, set it down as a general principle, that when the stamina equal the pistillum in length, they move towards it; but if they are fixed below the style, then this bends down towards them. Of this we (hall now give some examples.

If we observe the styles of the passionflower immediately after the expansion of the corolla, we flail find them erect and close to one another in the centre of the flower. In a few hours <hey separate and lower themselves to

on theit living principle, to which we cannot refuse the name of irritability. This power of motion has been generally acknowledged and allowed in the leaves of a great many plants, why then should it not be admitted in those; organs, the motions of which are at least as constant and as evident ? Both appear to depend on one cause, that is, the vegetable life ; and how indeed can we conceive that any plant should be fecundated without allowing a principle of irritability in the organs destined for its reproduction?

It may here be asked, why the sexual organs exhibit no signs of iiri

wards the stamina, in such manner, lability except at the time os fecundathat each stigma touches the anthera tion, while this power is always ready that corresponds to it; and after they to act in the leaves or other parts that have been impregnated they withdraw, possess it? The answer seems to me Those os the nigella have a motion to be plain. We know that these orOearly similar, and even more evident, gans do not arrive at their perfectioa Before fecundation, their styles are till after the expansion of the flower, strait, like those of the pasEon-flower, and that they fade when the fecunda.ar.d stand close together in the middle tion is performed; while the leaves of the flower. As soon as the an- continue in a state of perfection for a theræ begin to allow their pollen to long time, and therefore it is not furescape, the styles make a curve, and prising that their irritability should alpresent their stigmata to the stamina ways be ready to exert itself. The that are placed below them, after which sexual organs of plants have even in they rife up and reassume their former this respect som* analogy with those vertical situation. These motions are of animals.

easily observable. Linnæus has described them in the flowers of the »/'gel/a aruensts. The style of the /;'//

This contraction of the different parts may perhaps be mechanically accounted for, by supposing larger vessels

um superbwit bends itself towards the on one side of a filament, or of a style, stamina, then leaves them after it has than on the other, in which the juices Been fecundated. The fame thing may circulate with greater rapidity at takes place in the fcrophulariag. the time of ttcyadauvn. By this sup

Vot. VII. No 41. U w pvliuon,

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