logical acuteness, conceived the idea of what is now universally recognised as the natural system of botany.

Properly speaking, this system is subject to no kind of artificial arrangement: it consists of certain groups called natural orders, all of which are, or should be, independent of each other; and the characters of which are derived indifferently from every part of the plant. But as it would be extremely embarrassing to the student to acquire a just notion of these groups, unless some mode were devised of analysing their characters, several plans have been invented by which the groups have been reduced to a sort of artificial arrangement, with greater or less violence to their mutual affinities. As all these plans must, as has been shown, necessarily be linear, the real affinities of plants must be very imperfectly indicated by them they are, therefore, of no value whatever, except for the purpose of facilitating investigation. They must be understood to form no part of what must strictly be called the natural system; they may be varied at pleasure, according to the ingenuity of the botanist; and that will be the best which is most facile, and which, at the same time, offers the fewest interruptions to the series of mutual relations. At present I think there are few botanists who will deny that they are all extremely defective; and that one of the greatest services that could be rendered to systematic botany would be to devise some scheme by which the orders could be better and more naturally arranged under their primary classes. Whoever does this will have to divest himself of all the prejudices, and they are not a few, which have grown up with the system of Jussieu, and that have taken deep root in the minds of his followers: he must judge for himself upon every single point that may come before him, and he must forget that any such artificial arrangements have existed as those of Jussieu himself, De Candolle, and others. It is even to be expected that the organs of vegetation will be, for this purpose, employed even more than those of the fructification; and that anatomical characters analogous to those which characterise the really natural primary divisions of Vasculares and Cellulares, and of Exogenæ and Endogenæ, will be applied to the grouping, in subordinate masses, of the orders themselves.

At present scarcely any attempts of this nature have been made, except by Agardh and Bartling; but the endeavours of those botanists, however meritorious, are far from coming up to what may be expected.

The first outline of the natural orders that are now adopted was given to the public by Jussieu in 1789, in the following form:

Appended to these is a list of genera, the characters of which were not at that time sufficiently well known to enable Jussieu to refer them to any of the preceding orders. They are arranged according to the following artificial plan:

1. Monopetalous with a superior ovarium.
2. Monopetalous with an inferior ovarium.
3. Polypetalous with a superior ovarium.
4. Polypetalous with an inferior ovarium.

5. Apetalous, hermaphrodite, with a superior ovarium.
6. Apetalous, hermaphrodite, with an inferior ovarium.
7. Apetalous, diclinous, with a superior ovarium.
8. Apetalous, diclinous, with an inferior ovarium.

In this attempt, which may be truly pronounced the most important event which has occurred in botany, next to the universal reformation of natural history by Linnæus, advantage was taken of an arrangement used in the Trianon Garden in 1759, by Bernard de Jussieu, in which the natural affinities of plants had been seized in a manner that is perfectly surprising, if we consider how little was known at that time of those anatomical peculiarities upon which the natural affinities of the vegetable kingdom are now determined.

Since the date of 1789, alterations, additions, and improvements in the system of Jussieu have been constantly making. For these the world is chiefly indebted to Jussieu himself, our celebrated countryman Mr. Brown, De Candolle, the late Louis Claude Richard, Kunth, Auguste St. Hilaire, Von Martius, and a few others. These have given a new feature to the system, and have brought it to a far more advanced state of completeness than, perhaps, could have been expected in the short space of thirty or forty years. To show what that state is, and the existing notions relating to the limits of natural orders, would occupy much more space than could be spared in the present work. The student will find ample information upon the subject in my Introduction to the Natural System of Botany, published in 1830.

CHAPTER IV.

OF SPECULATIVE MODES OF ARRANGEMENT.

BESIDES the two principles of classification now explained, there is a third, which has arisen in the minds of certain German metaphysical naturalists, and which they conceive to be the true natural system; but which may more properly be termed a speculative attempt at forming a system by the mere force of reason, without attending to the facts upon which any system must depend. While other naturalists take facts as the basis of all arrangement, and accommodate their system to the data they possess, the authors of the speculative modes of classification first form a system from the idea that all matter is subject to the influence of certain universal causes, which prevail equally in every kingdom of nature; and then attempt to adjust facts to the arrangement thus formed by the mere force of imagination. Strange as this doctrine seems, and foreign as it may appear to every principle of sound philosophy, yet, as it is possible that some useful ideas may be elicited even from the wildest of such speculations, I shall avail myself of an excellent exposition of the subject by M. Choisy, of Geneva, to give some account of the doctrines in question.

The first principle, they say, to be inculcated is, that there is a fundamental difference between philosophical and empirical science: there is, says Nees Von Esenbeck, a speculative, and also an experimental, knowledge of things; the first is dependent upon a pure conception of nature, the last relies upon material observation. In consequence of thus distinguishing two methods, these philosophers consider themselves enabled to establish what they call unity, which is their leading dogma; and by which they mean the existence of some single power that overrules all other powers, and determines the structure and existence of every thing. By the aid of such facts as are applicable to their particular notions, each