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mous plants. He applied it indiscriminately to those species where he obtained some indistinct view of sexual organs, and to others where he never had the slightest glimpse of any. His doctrine was, that every organized being is endowed with the faculty of propagating itself either by egg or by seed; that an egg or a seed could not be produced without impregnation; and consequently, no organized being is destitute of male and female. organs, though these may not be discernible by the eye of the observer. Subsequent investigations have however led to the opinion, that there do exist organized beings that produce neither egg or seed; and that others possess these means of multiplying themselves independently of previous impregnation; and most botanists of the present day agree, that the presence of sexual or gans in many species included by Linnæus in his cryptogamous class of vegetables, is any thing but proved.

If we adopt the latter opinion, which appears to rest upon solid ground, it follows, that we should divide the vegetable system into three primary divisions, instead of two: the first, comprising the phænogamous species, where the process of fecundation is palpable; the second, the cryptogamous ones, where that process is involved in some degree of obscurity; the third, the agamous ones, in which no such process takes place.

Equal to the facility we may experience in forming a conception of three such classes in a general point of view, is the difficulty we shall find in determining the boundaries of each with precision. Experiment is undoubtedly the most direct test of the presence of the sexes. We can be at no loss concerning the office of the stamens, when we perceive that the ovula constartly miscarry in the most perfectly constituted germen, if the pollen has not reached the stigma; and on the other hand, find that the same as unfailingly come to perfection wherever the pollen arrives at the destined point.

A less direct test, but one that may be as safely depended upon, is analogy, and it is better suited to our daily purposes. We admit without hesitation, a multitude of plants into the ranks of the phænogamous species, upon which it has never entered our head to try any direct experiments in regard to the powers of

fecundation, being satisfied, by a comparison of the organization of their flowers with that of the few in which the existence of the sexes have been directly demonstrated, that we are entitled to acknowledge their being qualified with stamens and pistils. But in cases, where on one hand the analogy of the organs, grounded upon the similitude of forms, is not clear; on the other, the structure and the minuteness of the parts preclude the possi bility of the test by experiment; it is easy to conceive, that the existence of the sexes may become a question; and this is what has actually taken place in regard to a good many plants, which have been ranked by each botanist, in his turn, according to his own particular views; at one time in the phænogamous, at another in the cryptogamous, at another in the agamous class. Iu this way opinions have become divided. One plant has been known to change its place as often as it has been examined. Another, after having been deposited by common assent, in one of the two classes of which we are now speaking, to this hour affords a handle for controversy, because it has not been possible to adduce strict proof of the office of each organ; hence it is, that both in the agamous and in the cryptogamous plants, the appellations of stamen, pistil, anther, germen, pollen, seed, propagulum, &c. &c., have been all applied in their turn to the same part in the same species by different botanists; and that systems. have gone on multiplying as fast as any fact in regard to organization, that had escaped preceding observers, has been brought forwards by succeeding ones.

If we give due weight to these circumstances, we shall be convinced, that a different line is to be pursued in reviewing the agamous and cryptogamous department of vegetation, from the one we have had to pursue in considering the phænogamous portion; for here our object cannot be to lay down general positions, and bring into one point of view all that belongs to each system of organs apart, because the forms are extremely various, and their functions, and of consequence their analogies, are more within the scope of conjecture than of demonstration. The method we have to pursue is to confine ourselves to the study of each group by itself, keep separate the facts which are

revealed by nature, from those which are to be found only in the conventional systems of man, and upon a final scrutiny, to abide by the doctrine which seems to afford the greatest degree of probability, without blinking the weak and hypothetical parts which may belong to it. We shall review in succession the Salvinia, Equisetacca, Musci, Hepatice, Lycopodiacea, Filices, Alga, Lichenes, Hypoxylea, and Fungi. In proceeding in this order, we pass by gradually changing shades of difference from the species which approach the nearest to phænogamous vegetation, to those which recede the farthest from it.

Before we enter into the detail of our subject, let us premise a few words concerning the texture of the substance of plants of this nature.

A membranous and cellular texture belongs to the substance of all plants, but subject to a vast variety of modifications, all which modifications are not found to exist in every species. We are acquainted, for instance, with certain phænogamous species, in which neither trachea, false tracheæ, nor moniliform vessels are to to be found. None of these modifications of texture belong to the mushrooms, liverworts, hypoxyleæ or alga, which are most probably all of them of the agamous class. The substance of these consists of a mass of continuous cells of various elongations, with membranous walls of various thickness; and their outer skin or epidermis, which can seldom be detached from the rest of the texture, is without miliary glands. Excepting the algae, the plants of this class have no parts of an herbaceous nature.

The other groups, viz. the Ferns, Lycopodiaceæ, Hepaticæ, Mosses, Horse-tails, and Salviniæ, do not appear to differ from those of the phænogamous class in the nature of their texture; leaves, or else herbaceous processes that serve the turn of leaves, and vessels, have been observed in the greatest part of them. Struck by this analogy to the phænogamous plauts, some authors have concluded from thence, that the plants of these groups could not be without sex; not a very consequential way of reasoning at all events, since it is not yet proved that the presence of trachea, false tracheæ, miliary glands, leaves, &c. &c., necessarily imply that of stamens and pistils. Let us lay

aside all such groundless conclusions, and keep close to the detail of facts.

SALVINIE.

This group consists of the genera PILLULARIA (Pill-wort,) MARSILEA, SALVINIA, and ISOETES (Quill-wort,) all aquatic plants, which are to be found in France. We place it at the head of the ranks of the cryptogamous class, as other botanists have done before us.

PILLULALIA grows in wet places. Its creeping stem puts out small branches at different points; these produce slender cylindrical leaves, at first like a sheep-crook; at the foot of each branch arises a globular involucre, as large as a pea, without any opening; this involucre parts itself into four pieces, which then constitute four distinct cells, each containing from sixteen to twenty pistils, and from thirty to two-and-thirty anthers; the pistils are situated in the lower part of the cell, and have an obtuse stigma, the anthers are collected in a round tuft, and are suspended from the top of the same cell; these last are conical, and open transversely at the top; their pollen consists of globular grains, which do not burst when they come in contact with water; each pistil is provided with a seed that germinates by a leaf.

Linnæus, who had taken but a very superficial view of PILLULARIA, but was determined to find sexual organs in that as well as all other plants, supposed the involucre to be one entire pistil, containing several ovula, and that the pollen was disseminated over the leaves. But Bernard de Jussieu, by explaining the true structure of the sexual organs of this genus, has completely refuted the opinion of Linnæus. Nor can it be said that it was one founded upon observations of the least weight, or supported by any evident analogy; but stands a proof with how little circumspection even the most skillful authors make assertions in aid of any favourite system they have to build up. A reflection that will often obtrude itself into our minds, as we proceed.

MARSILEA has a stem which creeps along the ground, the same as in PILLULARIA; but here there are long petioles which

bear at their top four leaflets, disposed In the form of a cross, and near their base eggshaped involucres that do not open. The cavity of the involucres is divided lengthways into two cells, which are subdivided into several compartments, containing pis. tils and anthers mingled together. The anthers are very numerous and very small, do not open, have but one cell, and are filled with a pollen consisting of opaque grains; the pistils are not numerous; they are provided with a style, and contain within a double membrane, a granular transparent matter. This is the sum of what we collect from the observations of Bernard de Jussieu and Mr. Robert Brown; but in admitting that the facts stated by these skillful botanists are correct, yet the appellations of pistils, stamens, and pollen, may after all be misapplied, for experience has not yet taught the real uses of any of the organs of this genus.

SALVINIA floats on and extends itself over the surface of stagnant waters, in the form of a lively verdant carpet. Its branches are furnished with small opposite oval leaves, sprinkled with minute glands surmounted by four spirally curled hairs; from under the pairs of leaves, and among the roots, are produced in groups several close globular involucres of about two centimetres in diameter. There is only one female involucre in each group; the rest are males, and contain from one to two hundred whitish globular anthers, each with a small filament of its own, by means of which the whole are collected in bunches upou a common shaft. The female involucre encloses from ten to twelve white oblong chagreened pedicled pistils, which become as many small capsular fruits, with one small seed (seminulum) in each. All these involucres separate from the parent. plant towards the end of summer, and sink to the bottom of the water. In the following month of April, the capsules having rid themselves of the involucre, rise again to the surface of the water, and germination takes place. At first the capsule opens at the top by three teeth; then two radicles, like two little horns, are evolved; then a petioled leaf makes its appearance in the form of an inverted crescent; when the stem at last issues from the sinus in the leaf.

Linnæus had taken a false view of the sexual organs of SAL-
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