practical value; showing, by the use of the microscope, that the law was applicable not only to the external parts of plants, but to the development of their tissues also. Besides the debt which science owes to Robert Brown, he contributed largely to perfecting the natural method of classification. His great work upon the Hora of Australia has greatly extended the circle for that comparison of characters which is the basis of ‘botanical genera and tribes, The number of families admitted in the present day as the result of the investigations of the eminent men whose names have been mentioned, and many others which could not be quoted here without swelling our pages to undue proportions, number THREE HUNDRED AND THREE; and many of these are again subdivided by botanists who have made certain families their special study.

We have had a tabular view of the vegetable world as arranged by Adrien de Jussieu. According to the modifications introduced by De Candolle, plants are divided into two great classes, Crypto-gumes and Phanerogames.

The Crryprocamra, from ydpoc, nuptials, and ypumrdc, hidden, are destitute of pistils and stamens: they are reproduced by means of divers organs which seem to have no other analogy, except by their functions, with the reproductive organs in other plants. They Present no cotyledon, and yet they cannot be classed among acotyledonous plants. e PHANEROGAMES, from yéo¢ and pavepéc, visible, have perceptible reproductive organs formed of stamens and ovules, naked °r enclosed in a kind of pistil.

According, then, as Phanerogames have an embryo furnished With one or two cotyledons, they are divided into two great natural 8roups, the Monocotyledons or Dicotyledons.

Adrien de Jussieu divided the Cryptogames, as we have seen, in to two classes: Cellular Cryptogamia, including those composed of a vegetable tissue only, not traversed by vessels; and Vas-ove Cryptogamia, those provided with vessels. As regards hanerogamia, he arranged them in one great division, calling = Monocotyledonous Phanerogames; distributing them, however, into two classes—(1) or Gymnospermes, naked-seeded, from yupvec, naked, and orépua, seed; and (2) Angiospermes (plants with seeds

enclosed in the fruit), from ayyciov, capsuled, and ozéppa, seed. The dicotyledonous gymnospermes of De Jussieu formed only five families, and comprehended what we call Evergreens; the dicotyledonous angiospermes were divided into many secondary groups, whose distinctive characters were drawn from peculiarities of the — reproductive organs. Whilst the labours of the eminent men we have named were laying the foundations of the science, assisted by others only a degree lower, both in France and Germany, English botany was laying its own foundations. Robert Brown was no systematist. He was much struck with Goethe’s ideas of the morphology of plants. Working with the microscope, he applied the theory to the development of the tissues of plants; and every new fact served to confirm him in the belief that the principle was universal. But the man of all others to whom modern science is most indebted for perfecting the botanical arrangement of plants, is the late Dr. Lindley. His knowledge of vegetable structure was extensive and profound. His indefatigable industry and unequalled powers of generalisation enabled him to grapple with and bring to perfection the vast scheme of re-arranging on physiological principles, after careful structural examination, the whole vegetable world. ” “Vegetable Kingdom” remains a monument of immense learning technical knowledge, and vast industry. The modern school of botanists may be said, one and all, to have been his pupils, and the system he has framed is probably the nearest to perfection which the world has yet seen; and M. Figuier must excuse the editor of the English translation when he adopts a system which has superseded all others in the British schools.

The basis of this system is a close examination of the minuter parts of plants, particularly the seeds; since, of all parts of plants, that is the one which displays the greatest constancy- diff-culties in comprehending it lie at the threshold; and in overcoming them the student has the gratification of gaining a vast amoun The following is a brief condensatio? information.of interesting of P.rofessor Lindley’s scheme frcm the “ Vegetable Kingdom: (p. lv. e¢ seq.), whose parting advice to his readers is, to bear mind that under the natural system the stamens and pi ils play* subordinate part, and are only accounted as a portion of the whole:

plant; but very minute and constant attention should be directed to the ovule and the seed, so that a pocket magnifier of moderate power is absolutely necessary in examining plants on this system.” We can only give an outline of this great scheme, following it up with a short notice of the orders, and filling up the sketch with a few details of the species most interesting toman. The object of a systematic arrangement of plants being to bring together groups according to their apparent relationship to each other, that adopted by Dr. Lindley classes them as—(1) Thallogens, from @éXapoc, the bridal chamber; (2) Acrogens, from axpos, topmost, and yevaw, to produce; (3) Rhizogens, from pfopa, a root; (4) Endogens, from evéov and yervaw, produced within; (5) Dictyogens, netted, from ourve, a net, and yevecda, to be; (6) Gymnogens, from yuproe. naked; (7) Exogens, from e& and yeveo8ar, to grow by external additions. The Acrogens are here identical in their limits with the Acotyledons of De J ussieu, the Exembryonate of Richard, the Celullares of De Candolle, the Agame of various authors, and the Cryptogamia of Linneus. The term itself is, however, only applicable literally to flowerless plants, which possess a stem growing like the Exogens, 80 that the stemless plants are classed as Thallogens. This is, however, but an artificial character; and some recent botanists allogens as a section of Acrogens.

ASEXUAL OR FLOWERLESS PLANTS:

A Thallus is a fusion of root, stem, and leaves into one general mass, and Thallo-i. THALLOGENs. ba Stems and leaves impercep- j gens are also destitute bn flowers, without ble ig, and they multiply by the

| formation of spheroids, called spores, in

\ their interior or upon their surface. )

( Beyond Thallogens are multitudes of )

qT, AcRoGENs "aren Stems and leaves quite per- } stems distinctly separated; some o om. ceptible, having the spiral filament whichis supposed to belong to a higher structural development; finally they multiply by reproductive spores like the Thallogens. Their stem, however, does notnot iincrease in diiameter, b but at their ) summit, as the name of the class indicates.

SEXUAL OR FLOWERING PLANTS.

The Rhizogens are a collection of anoms-lous plants, mostly leafless and parasitical, having the loose cellular organisation of Fungi, although traces of a spiral structure are usually found among their tissues, Some.

| of them spring directly from the shapeless

4 as.. and root, and seems to be analogous to the Thallus of the Fungi. Their flowers resemble those of more perfect plants; sexual organsare complete, but their embryo, which is without any visible radicle OF cotyledon, simply appears to be & spherical \ or oblong homogeneous mass. { In Endogens the germination 1s endor- Fructification sprung from a | hizal, whose embryo has but one cotyledon, Stem. Wood of stem youngest | whose leaves have parallel veins, and whose at the centre; cotyledon single. 4 trunk is formed of bundles of spiral and Leaves parallel veined; perma- | dotted vessels, guarded by wooded tubes arranged in a confused manner, and are reproduced in the centre of the trunk, Fructification springing from | cellular mass which serves at once for stem a Thallus.

IV. ENDOGENS .

nent woody stem confused. Dictyogens are distinguished from Tindo-gens by the roots, which have no cone tric circles, and the leaves fall off the stem by a clean fracture, as in that class. i 0 “ Gymnogens are Exogens, which have n vie the emia: style or stigma, the reproductive organs Deciduous; leaves net-veined: wood of the stem, when perennial, arranved in a cirele with the central pith.

V. DICTYOGENS ,.

centric, and youngest at the lien falls in '; being so constructed that the pe, ‘ire n - - ' as a c- —— ~— immediately upon the ovules, & pec uliarity . —— analogous to what occurs among Fe or more. Seeds quite naked. enallieectinctadions rable cases Exogens consist of innume having exorhizal germination; 4D — with two or more cotyledons; —_ per net-work of veins; trunk consisting 0, bundles, composed of dotted and

V1. GYMNOGENS

io round tubes or woody tubes alone, arranged row’ a central pith, either in concentric — in a homogeneous mass, but always ~~ medullary plates forming Tays — ~~ centre to the circumference, and repr on the circumference of the trun their name. VII. EXoGENS Seeds enclosed in seed vessels. k; whence

Fig. 295. THALLOGENS. The Thallogens of recent botanists correspond in all respects with the Cryptogamia of older botanists, a name given to this division of the vegetable world, not from their reproductive organs being Invisible, as has long been admitted, but from their being incon- ‘picuous, and requiring close observation, and some exact knowledge of their organisation, in order to discern them. If we enter °n a somewhat minute investigation of this important group, we are led to do so by the consideration that their organisation, Structure, and development is not usually attempted in elementary botanical works; and we feel assured that the interest and novelty of the observations we shall have to offer will be our apology for the relative extent of our descriptions. The division includes vegetables destitute of stamens and of Pistils, whose embryo is simple, homogeneous, and without distinct linen. grad number of them are of minute microscopic =e ons; their reproductive ongens eam only be distinguished © small. ¢, 4 a lens or a microscope. Nevertheless, these being inn aon 1umble, and to all appearance all but forgotten in of wn _ temerr. fulfil an important part im the economy source of al. ey constituted the first origin, and were even the Vegetable rycen Disaggregating rocks, they produced the The eng; h which became the means of their own destruction. ched soil nourished plants of more complex organisation,

and these inferior beings were replaced by degrees by vegetable species of more perfect structure. All soil primitively sterile, all land recently emerged from the bosom of the waters, served first as the asylum of crustaceous and foliaceous Lichens; at a later period Mosses and Ferns made their appearance there; finally, a superior» vegetation—namely, the Phanerogames, or Cotyledons—present themselves. Everything leads us to conclude that such has been the successive series of creations upon our globe, when it was sufficiently cooled on the surface to admit of organic life, and when the islands and continents were sufficiently elevated above the universal ocean of the ancient world to permit them to live.

Thus the higher orders of vegetables have only appeared, and will only continue to make their appearance, upon the débris of vegetation of a lower order.:

But, on the other hand, by one of those striking contrasts of which Nature offers more than one example, vegetables of a supeTio® order, when they are struck by death—sometimes even during their existence—are often the prey of humbler Thallogens, which attach themselves as parasites to these princes of the vegetable world, and devour them in the end; their destructive action 1s all-powerful and everywhere; it respects the works of man no more than the works of nature. j

To produce and to destroy life is, then, the double an‘ providential mission which devolves on the Thallogens. Nevertheless this multiplied work of creation and death is only bestowed and soe evanescent the first is an conditions:‘on them on two existence, the second is to multiply themselves to infinity ab with prodigious rapidity. There are some mushrooms which pr duce sixty thousand tetricales or cells per minute! The capsules of certain mosses enclose seeds of which it would require pa thousands to make a pin’s head in size. These seeds float free. SE" invisible in the air, which is in a sense saturated with them. pe

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