| OCR Text |
Show AN 'OTATIONS AND ADDITIONS. 293 candolle in France 3645 species of phrenogamous 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 120,000 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 Algre, funguses, and lichens), Characere1 liver-worts, mosses, Marsilacere, Lycopodiacere, 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 m1mma. 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 phrenogamous 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 (Agamre, 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 tro_ pical zone as 1 : 5, and in the cold zones of the parallels of 60° N. and 55° S. latitude, as 1 : 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 phrenogamous plants belonging to a zone 25* |
