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Show CHAPTER V. h' al distr1. buh. on of species-Analog.y of climate. Laws which regulate the geograp IC . · t . 1 geography-Stahons-Habi· not attended w1. th 'd t't f specles-Bo amca . 1 d 1 en 1 Y 0 1 t -Vegetation of Is an s- . . f indigenous P an s . tations-Distinct provmces o t b orne diffused-Effects of wmd, . I h t manner plan s ec h Marine vegetahon- n w a . 1 -Many seeds pass through t e . t Agency of ammo. s . . rivers manne curren s- . A cy of man in the dispersion ' db' ds und1gested- gen stomachs of animals an tr It alogy to that of the inferior of plants, both voluntary and involuntary- s an animals. i whether species have a real NExT to determining the quest on 1 h' 1 regulate their . h nsideration of the aws w lC 1 ' existence, t e co b' t f primary importance . 1 d' 'b t' is a su aec 0 geographiCa . Istri ~ Ion d inO' these laws with atten· to the geologist. It lS only by st~ y o s ecies occu tion, by observing the position which gro:ps o: lin the cou;:e at resent, and inquiring how these may e.varie and of ~me by migrations, by changes in phyhsictlal g:~:~:~ion of l t hope to learn w e 1er other causes, t la we can . h t f the animate . b limited or in what manner t e sta e o species e ' f 1 · imate ld l·s affected by the endless vicissitudes o t le man . ,l wor · b b'ted by entire y That different regions of the globe are m a 1 .£' '1' to distinct animals and plants • .e 1 . h h been !ami Iar IS a 1act w nc as f i-Gc all naturalists since Buu.~ro n fi rst pom. t ed out the want do thspoesce: ro f identity between the land quadrupeds of America aln times the Old World. The same p 1l enomeno n has ' in .a ter the' been forced, m. a stn'k 'm g manner., upo n our attentwn, b·y 5 of . t' f New Holland where the m· d'I genou s speCie . examma wn o ' . t exceptiOn, animals and plants were found to be, almost withou distinct from those known in other parts of the world. gst But the extent of this parce1 1.m g ou t 0 f the globe amdo n i· different nations, as they have been terme d ' of plantds' anr y aann d mals,-the universal.i ty of a p h enomeno n so extraor . mtear esting unexpected may b.e cons1' de re d as one of the most m. facts clearly' established by t h e a d vance 0 f modern sCience. Clt.V.] BOTANICAL GEOGRAPHY. 67 Scarcely fourteen hundred species of plants appear to have been known and described by the Greeks, ltomans, and Arabians. At present, more than three thousand species are enumerated, as natives of our own island >X\ In other parts of the world there have been collected, perhaps, upwards of seventy thousand species. It was not to be supposed, therefore, that the ancients should have acquired any correct notions respecting what may be called the geography of plants, although the influence of climate on the character of the vegetation could hardly have escaped their observation. Antecedently to investigation, there was no reason for presuming that the vegetable productions, growing wild in the eastern hemisphere, should be unlike those of the western, in the same latitude ; nor that the plants of the Cape of Good Hope should be unlike those of the South of Europe ; situations where the climate is little dissimilar.. 'l'he contrary supposition would have seemed more probable, and we might have anticipated an almost perfect identity in the animals and plants which inhabit corresponding parallels of latitude. The discovery, therefore, that each separate region of the globe, both of the land and water, is occupied by distinct groups of species, and that most of the exceptions to this general rule may be referred to disseminating causes now in operation, is eminently calculated to excite curiosity, and to stimulate us to seek some hypothesis respecting the first introduction of species which may be reconcileable with such phenomena. A comparison of the plants of different regions of the globe affords results more to be depended upon in the present state of our knowledge, than those relating to the animal kingdom, because the science of botany is more advanced, and probably comprehends a great proportion of the total number of the vegetable productions of the whole earth. Humboldt, in several eloquent passages of his Personal Narrative, was among the first to promulgate philosophical views on this subject. Every hemisphere, says this traveller, •. Barton's Lectu1·es on the Geography of Plants, p. 2. F2 |