44 FLORIDA REEFS. 



the slope of a high mountain in the Tropics, from base to summit, presents 

 in a condensed form, an epitome, as it were, of the same kind of gradation 

 in vegetable growth that may be observed from the Tropics to the Arctics. 

 At the base of such a mountain Ave have all the luxuriance of growth 

 characteristic of the tropical forest, — the palms, the bananas, the bread- 

 trees, the mimosas ; higher up, these give way to a different kind of growth, 

 corresponding to our oaks, chestnuts, maples, &c. ; as these wane, on 

 the loftier slopes comes in the pine forest, fading gradually, as it ascends, 

 into a dwarfish growth of the same kind ; and this at last gives way to the 

 low creeping mosses and lichens of the greater heights, till even these find 

 a foothold no longer, and the summit of the mountain is clothed in per- 

 petual snow and ice. What have we here but the same series of changes 

 through which we pass, if, travelling northward from the Tropics, we leave 

 palms and pomegranates and bananas behind, where the live-oaks and 

 cypresses, the orange-trees and myrtles of the warmer temperate zone 

 come in, and these die out as we reach the oaks, chestnuts, maples, elms, 

 nut-trees, beeches, and birches of the colder temperate zone, these again 

 waning as we enter the pine forests of the Arctic borders, till, passing out 

 of these, nothing but a dwarf vegetation, a carpet of moss and lichen, fit 

 food for the reindeer and the Esquimaux, greets us, and beyond that lies 

 the region of the snow and ice fields, impenetrable to all but the daring 

 arctic voyager ? 



I have thus far spoken of the changes in the vegetable growth alone 

 as influenced by altitude and latitude, but the same is equally true of 

 animals. Every zone of the earth's surface has its own animals, suited to 

 the conditions under which they are meant to live ; and, with the exception 

 of those that accompany man in all his pilgrimages, and are subject to the 

 same modifying influences by which he adapts his home and himself to all 

 climates, animals are absolutely bound by the laws of their nature within 

 the range assigned to them. Nor is this the case only on land, where 

 river-banks, lake-shores, and mountain-ranges might be supposed to form 

 the impassable boundaries that keep animals within certain limits ; but the 

 ocean, as well as the land, has its faunae and flora) bound within their 

 respective zoological and botanical provinces; and a wall of granite is not 

 more impassable to a marine animal than that ocean-line, fluid, and flowing, 

 and ever-changing though it be, on which is written for him, " Hitherto 

 shalt thou come, but no farther." One word as to the effect of pressure 

 on animals will explain this. 



