| OCR Text |
Show 310 PHYSIOGNOMY OF PLANTS. flowering plants must be sought for in tropical countries, and in the latitudes from 12° to 15° distant from the tropics. It has appeared to me not unimportant to show the imperfect state of our knowledge in this still little cultivated department of arithmetical botany, and to propound numerical questions in a more distinct and determinate manner than could have been previously done. In all conjectures respecting numerical relations, we must seek first for the possibility of deducing the lower or minimum limits; as in a question treated of by me elsewhere, on the proportion of coined gold and silver to the quantity of the precious metal fabricated in other ways; or as in the questions of how many stars, from the lOth to the 12th magnitude, are dispersed over the sky, and how many of the smallest telescopic stars the Milky Way may contain. (John Herschel, Results of Astron. Observ. at the Cape of Good Hope, 1847, p. 381.) We may consider it as established, that, if it were possible to know completely and thoroughly by observation all the species belonging to one of the great families of phanerogamous or flowering plants, we should learn thereby at the same time, approximatively, the entire sum of all such plants (including all the families). As, therefore, by the progressive exploration of new countries, we progressively and gradually exhaust the remaining unknown species of any of the great families, the previously assigned lowest limit rises gradually higher; and since the forms reciprocally limit each other in conformity with still undiscovered laws of universal organization, we approach continually nearer to the solution of the great numerical problem of organic life. But is the number of organic forms itself a constant number? Do new vegetable forms spring from the ground after long periods of time, while others become more and more rare, and at last disappear? Geology, by means of her historical monuments of ancient terrestrial life, answers to the latter portion of this question affirmatively. 11 In the Ancient World," to use the remark of an eminent naturalist, Link (Abhandl. der Akad. der Wiss. zu Berlin a us dem J ahr 1846, s. 1322), 11 we see characters, now apparently remote and widely separated from each other, associated or crowded together in wondrous forms, as if a greater development and separation awaited a later age in the history of our planet." |
