lichens, giving it a pleasing appearance. Judging by the size of a small piece of wood which has been cut out above the door, and in which the marks of 200 annular rings have been counted, the oak of Saintes would be between 1800 and 2000 years old. (Annales de la Société d'Agriculture de la Rochelle, 1843, p. 380.)

;

In the wild rose-tree of the crypt of the Cathedral of Hildesheim, said to be a thousand years old, it is the root only, and not the stem, which is eight centuries old, according to accurate information derived from ancient and trustworthy original documents, for the knowledge of which I am indebted to the kindness of Stadtgerichts-Assessor Römer. A legend connects the rose-tree with a vow made by the first founder of the cathedral, Ludwig the Pious and an original document of the 11th century says, "that when Bishop Hezilo rebuilt the cathedral which had been burnt down, he enclosed the roots of the rose-tree with a vault which still exists, raised upon this vault the crypt, which was re-consecrated in 1061, and spread out the branches of the rose-tree upon the walls." The stem now living is 26 feet high and about two inches thick, and the outspread branches cover about 32 feet of the external wall of the eastern crypt; it is doubtless of considerable antiquity, and well deserving of the celebrity which it has gained throughout Germany.

If extraordinary development in point of size is to be regarded as a proof of long continued organic life, particular attention is due to one of the thalassophytes of the sub-marine vegetable world, i. e., to the Fucus giganteus,

or Macrocystis pyrifera of Agardh. According to Captain Cook and George Forster, this sea-plant attains a length of 360 English feet; surpassing, therefore, the height of the loftiest Coniferæ, even that of the Sequoia gigantea, Endl., or Taxodium sempervirens, Hook and Arnott, which grows in California. (Darwin, Journal of Researches into Natural History, 1845, p. 239; and Captain Fitz-Roy in the Narrative of the Voyages of the Adventure and Beagle, vol. ii. p. 363.) Macrocystis pyrifera is found from 64° south to 45° north latitude, as far as San Francisco on the northwest coast of America; and Joseph Hooker believes it to extend as far as Kamtschatka. In the Antarctic seas it is even seen floating among the pack-ice. (Joseph Hooker, Botany of the Antarctic Voyage under the command of Sir James Ross, 1844, pp. 7, 1, and 178; Camille Montagne, Botanique cryptogame du Voyage de la Bonite, 1846, p. 36.) The immense length to which the bands or ribbands and the cords or lines of the cellular tissue of the Macrocystis attain, appears to be limited only by accidental injuries.

(13) p. 17.—“ Species of phænogamous plants already contained in herbariums."

We must carefully distinguish between three different questions: How many species of plants are described in printed works? how many have been discovered, i. e. are contained in herbariums, though without being described? how many are probably existing on the globe? Murray's edition of the Linnean system contains, including crypto

gamia, only 10042 species. Willdenow, in his edition of the Species Plantarum, between the years 1797 and 1807, had already described 17457 phænogamous species, (from Monandria to Polygamia diœcia.) If we add 3000 cryptogamous species, we obtain the number which Willdenow mentions, viz. 20000 species. More recent researches have shown how much this estimation of the number of species described and contained in herbariums falls short of the truth. Robert Brown counted above 37000 phænogamous plants. (General Remarks on the Botany of Terra Australis, p. 4.) I afterwards attempted to give the geographical distribution (in different parts of the earth already explored), of 44000 phænogamous and cryptogamous plants. (Humboldt, de distributione geographica Plantarum, p. 23.) Decandolle found, in comparing Persoon's Enchiridium with his Universal System in 12 several families, that the writings of botanists and European herbariums taken together might be assumed to contain upwards of 56000 species of plants. (Essai élementaire de Géographie botanique, p. 62.) If we consider how many species have since that period been described by travellers,-(my expedition alone furnished 3600 of the 5800 collected species of the equinoctial zone), and if we remember that in all the botanical gardens taken together there are certainly above 25000 phænogamous plants cultivated, we shall easily perceive how much Decandolle's number falls short of the truth. Completely unacquainted as we still are with the larger portions of the interior of South America,-(Mato-Grosso, Paraguay, the eastern declivity of the Andes, Santa Cruz

de la Sierra, and all the countries between the Orinoco, the Rio Negro, the Amazons, and Puruz),—of Africa, Madagascar, Borneo, and Central and Eastern Asia,-the thought rises involuntarily in the mind that we may not yet know the third, or probably even the fifth part of the plants existing on the earth! Drège has collected 7092 species of phænogamous plants in South Africa alone. (See Meyer's pflanzen geographische Documente, S. 5 and 12.) He believes that the Flora of that district consists of more than 11000 phænogamous species, while on a surface of equal area (12000 German, or 192000 English square geographical miles) von Koch has described in Germany or Switzerland 3300, and Decandolle in France 3645 species of phænogamous plants. I would also recall that even now new Genera, (some even consisting of tall forest trees), are being discovered in the small West Indian Islands which have been visited by Europeans for three centuries, and in the vicinity of large commercial towns. These considerations, which I propose to develop in further detail at the close of the present annotation, make it probable that the actual number of species exceeds that spoken of in the old myth of the Zend-Avesta, which says that "the Primeval Creating Power called forth from the blood of the sacred bull 120000 different forms of plants!"

If, then, we cannot look for any direct scientific solution of the question of how many forms of the vegetable kingdom,including leafless Cryptogamia (water Algæ, funguses, and lichens), Characeæ, liver-worts, mosses, Marsilaceæ, Lycopodiaceae, and ferns,-exist on the dry land and in the ocean

in the present state of the organic life of our globe, we may yet attempt an approximate method by which we may find some probable "lowest limits" or numerical minima. Since 1815, I have sought, in arithmetical considerations relating to the geography of plants, to examine first the ratios which the number of species in the different natural families bear to the entire mass of the phænogamous vegetation in countries where the latter is sufficiently well known. Robert Brown, the greatest botanist among our cotemporaries, had previously determined the numerical proportions of the leading divisions of the vegetable kingdom; of Acotyledons (Agamæ, Cryptogamic or cellular plants) to Cotyledons (Phanerogamic or vascular plants), and of Monocotyledonous (Endogenous) to Dicotyledonous (Exogenous) plants. He finds the ratio of Monocotyledons to Dicotyledons in the tropical zone as 1 : 5, and in the cold zones of the parallels of 60° N. and 55° S. latitude, as]: 2. (Robert Brown, General Remarks on the Botany of Terra Australis, in Flinders' Voyage, vol. ii. p. 338.) The absolute number of species in the three leading divisions of the vegetable kingdom are compared together in that work according to the method there laid down. I was the first to pass from these leading divisions to the divisions of the several families, and to consider the ratio which the number of species of each family bears to the entire mass of phænogamous plants belonging to a zone of the earth's surface. (Compare my memoir entitled "De distributione geographica Plantarum secundum cœli temperiem et altitudinem montium, 1817, p. 24-44; and the farther development of the subject of these numerical