The System of Jiissieu

THE SYSTEM OF JIISSIEU Consists of fifteen classes, which are composed, all together, of one hundred orders. The characters of the classes depend first on the number of cotyledons ; next the number of petals, and the situation, or place of insertion, of the stamens and corolla.

The author uses the term stamina hypogyna for such stamens as are inserted into the receptacle, or below the germen, which therefore we shall call in ferior stamens ; stamina perigyna, (around the ger men), are inserted into either the corolla or calyx, the gernsen being superior ; these we must denomi nate perigynous ; stamina epigyna, superior stamens, are inserted above the germen, which latter is there fore, in Linniean language, inferior. The same terms apply to the corolla, which when inserted into the calyx is denominated perigynous. The fallowing table will show the characters of Jussieu's Classes: In the first place, it is evident that the great hinge, on which this system turns, is the number of the cotyledons. The importance of this character has, from the time of Csesalpinus and Jungius, been much insisted on. Linnieus, in his Preekctiones, p. 329, declares his opinion, that "the monocotyledo nous and dicotyledonous plants are totally different in nature, and cannot be combined ;" and that " if this distinction falls to the ground, there will never be any certainty. Not that characters should be taken from hence, but sections when formed should be confirmed by the cotyledons." So jealous was this great man of any definition of his natural orders! He subjoins an exception to the above rule, in Cuscuta and Cactus. which having no leaves, he supposes have no occasion for cotyledons. Linnets proceeds to observe that " the germination of parasitical phints requires investigation, but that he should greatly wonder if they have any cote ledons." We have already, under the llth of his Datum, orders, pointed out other exceptions, made by himself; to the rule just mentioned ; but in these he was partly, as we have shown, mistaken ; and had he been explicit about the &mien tacece , he probably would have proved himself in an error likewise with respect to them. Sc' Adiusson asserts the Juncos to ga.e two cotyledons, though the rest of its natu ral order have only one. But Gtertner has strated this genus to be monocotyledonous. - Adm. son mentions Orobanche and Cuscuta as monocotyle donous, which answers to the opinion of Linnaeus, but we know not how far this is just.

It appears that the line is distinctly drawn by na ture between plants with a simple or no cotyledon, and others with two, or more, and that, so far, the principle of Jussieu's classification is correct. Who, ther all the genera that he has considered as mono cotyledonous be truly so, is another question, which does not at all invalidate the distinction. Some have not been examined, and seem principally to be re ferred to that tribe, because; like others that indubi tably belong to it, they are aquatics ; or, at least, be cause of the apparent simplicity of their general structurtf. Doubts are expressed on this subject by Jussieu himself respecting Valisneria, Cronus (his Nelumbians), Trapa, Proserpinaca, and Puha. Some other genera, ranked as acotyledonous, are involved in similar uncertainty.

But with regard to the bulk of the

Acotykdones, composing the first of Jussien's classes, there seems to us much greater difficulty. Of his first three orders, Fungi, Alga and Hepahcce, nothing indeed is correct. ly known, except perhapi what Hedwig has published concerning Marcliantia and Antkoceros, and that is hardly sufficient for our purpose. With the fourth or der, Mucci, this great cryptogamist has made us so well acquainted, that they prove to be any thing else than acotyledonous, or ; at least if his idea of the parts be right. The parts which he takes for cotyledons are peculiarly numerous and complicat.• ed ; but we are ready to allow with Mr Brown, at conclusion of the preface to his Prod:rams Flora Nova Holkottlice, that these organs are of a most un certain nature, rather subsequent to germination than its first beginning, like what has been judged the coty ledon of Jussieu's 5th order, the Felice,. Yet hence

a new difficulty arises. The parts in question so complex in Mesa, are simple in Felice., insomuch that no analugy between these orders, otherwise so nearly akin, is to be traced iu those parts. On the other hand, it cannot be concealed that the plants termed ntonocotyledones have no cotyledon at all analogous to those of the dicotyledons; what Jussieu and others call such, being the albumen of the seed, absorbed in the first stage of vegetation. The minute plants as sumed to be acotyledonous, must be presumed to be furnished with something analogous, or we cannot conceive how vegetation can take place. By all these obeervations, we mean only to show, the the primary divisions of lussieu's system, are at least totally insuf. ficient to answer that practical purpose, which a stu dent has a right to expect from any methodical ar rangement. If the learned be still uncertain, whether the distinctions, on which such divisions are founded do, in a great number of cases, really exist, how can a beginner regulate his first inquiries thereby ? We are not the less ready to confess, that the difficulty in question is rather a philosophical speculation, than of any great practical importance. It gives a venerable air of mystery, which may procure respect for other parts of a system, that are more intelligible and more useful, though not free from exception. We allude to the next subdivision of the method of the great French teacher, founded on the petals. This should seem to be obvious and certain, but we soon find our , selves bewildered in an old labyrinth of dispute, con cerning the difference between a calyx and a corolla.. We are obliged to submit to a sweeping decision, which allows no corolla to monocotyledonous plants ; a decision which we cannot safely combat, because of the difficulty of deciding what are such, but which shocks our senses and our judgment, and seems refut ed in many instances by Nature herself, as decidedly as any of her laws can be established. Nor do we get clear of this perplexity among the declared dico tyledonous tribes, where the evident corolla of the Marvel of Peru is assumed to be an inner calyx, there being a- real perianth besides, subsequently indeed called an involacrans. Yet we are at a loss to discern wby the terminology here used, should have been dif ferent from that applied to the next order, Plumba since. We are ready, most unreservedly, to admit the great difficulty of decision in these cases, as well as in others, occurring in Jussieu's 5th, 6th, and 7th classes ; but that very difficulty evinces the precariousness' of making any thing connected with this most disputable of all questions, a primary guide in a system of methodical arrangement. When we proceed a step further, and come to the insertion of the stamens, the convenience and clearness of the system indeed improve upon our view ; but we must not hope to escape exceptions or inaccuracies, the connection of the /dements with the corolla being, by no means, uniform or constant, in the orders so cha• racterized, or even in all the species of particular genera, classed upon that principle. $o likewise the insertion of the stamens into the calyx is attended with such inveterate difficulties, that one of the warm -est promulgators and defenders of Jussieu's system, Mr Salisbury, has thought it easier to deny the exist ence of any such insertion, than to make it sub servient to practical use. We are indeed satisfied that the characters 'throughout the celebrated method of classification now under our contemplation, are at tended with as much difficulty and exception as those of any other system,-and we cannot but agree with Mr Roscoe, Trans. of the Linn. Soc. Vol. XI. 65, that it forms several as unnatural assemblages as even the professedly artificial .system of Linnaeus. With regard to practical facility, no person of judg ment has ever attempted to invalidate the superiority of the latter.