26 FINAL CAUSES. 



of structure, which they offer to our observation, is the la- 

 borious, yet fascinating, occupation of the Botanist. Here, 

 also, we are lost in admiration at the never-ending variety 

 of forms successively displayed to view in the innumerable 

 species which compose this kingdom of nature, and at the 

 energy of that vegetative power, which, amidst such great 

 differences of situation, sustains the modified life of each in- 

 dividual plant, and which continues its species in endless 

 perpetuity. Wherever circum.stances are compatible with 

 vegetable existence, we there find plants arise. It is well 

 known that, in all places where vegetation has been estab- 

 lished, the germs are so* intermingled with the soil, that 

 whenever the earth is turned up, even from considerable 

 depths, and exposed to the air, plants are soon observed to 

 spring, as if they had been recently sown, in consequence of 

 the o-ermi nation of seeds which had remained latent and in- 

 active during the lapse of perhaps many centuries. Islands 

 formed by coral reefs, which have risen above the level of the 

 sea, become in a short time covered with verdure. From the 

 materials of the most steril rock, and even from the yet 

 recent cinders and lava of the volcano. Nature prepares the 

 way for vegetable existence. The slightest crevice or ine- 

 quality is sufficient to arrest the invisible germs that are al- 

 ways floating in the air, and affords the means of sustenance 

 to diminutive races of lichens and mosses. These soon 

 overspread the surface, and are followed, in the course of a 

 few years, by successive tribes of plants of gradually in- 

 creasing size and strength; till at length the island, or other 

 favoured spot, is converted into a natural and luxuriant 

 garden, of which the productions rising from grasses to 

 shrubs and trees, present all the varieties of the fertile mea- 

 dow, the tangled thicket, and the widely spreading forest. 

 Even in the desert plains of the torrid zone, the eye of the 

 traveller is often refreshed by the appearance of a few hardy- 

 plants, which find sufficient materials for their growth in 

 these arid regions: and in the realms of perpetual snow 

 which surround the poles, the navigator is occasionally 



