Page:Books from the Biodiversity Heritage Library (IA mobot31753002447982).pdf/9

 bring together, under the name of alliances or classes, groups of allied orders which are occasionally widely separated by the procrustion operation of linear characters. But though much has, by these and other similar attempts been ef- fected to improve our arrangements, I still think we are far behind Zoology through our not having yet discovered in our Exogenous and Endogenous groups, those almost self-evident secondary divisions or circles so clearly marked out by nature in the animal kingdom, and so ably taken advantage of by Zoolo- gists, in working out their animal system.

To discover these, if they actually exist in Nature, appears in the present state of the enquiry to be the first and grand desideratum towards the discovery of the true Natural System of plants. In the mean time however, our establish- ed orders and genera being for the most part pretty nearly natural, aided by the convenient practical grouping now in use, serves all the purposes of a more strictly correct and philosophical arrangement, leaving us for the time, very inde- pendent of a better, and allowing us to proceed at our own pace, leisurely feeling our way, while searching for the long and ardently desired natural one. And it is in the hope that some of the readers of this exposition of what is wanted, to- wards the construction of the basement of the natural system of plants, may be induced to turn their attention to the subject and perhaps that some one luckier than the rest, may stumble on a clue which will lead himself or others to the desiderated point and enable him, by the formation of truly natural secondary groups or circles, to complete at least the lower tier of the edifice.

It only now remains for me to offer a few remarks on vegetable organi- zation, with reference to its employment in the construction of a Natural System of Botany. These must unavoidably be brief and imperfect, and probably, so far as they go, little to the point, the ideas of Botanists on this obscure subject being far from precise or settled on a firm basis, especially in what relates to the comparative value which should be assigned to each part, engaged in the com- plex organization of an Exogenous plant.

The organ principally regarded as the basis of all our attempts to obtain a natural arrangement is the Embryo, when present, taken in connexion with the plant which springs from it, whether, in short, it is mono-or di-cotyle- donous, giving origin to an Endogenous or Exogenous plant or is altogether ab- sent as in Acrogens; plants still further distinguished from those of the two higher groups by their Cellular texture and the nearly total absence of vascu- lar tissue.

Dicotyledonous or Exogenous plants have a woody stem, varying in solidity with their age from the tender herbaceous annual up to the almost stony hard- ness of the iron wood tree: increasing, with some exceptions, in thickness by the annual addition to the surface, layer upon layer, of new wood, forming rings or