NATUHAL HISTORY OF PLANTS,. 23 



Aquatic plants, while they remain under water, have their leaves 

 finely divided ; hut when they rise above the surface of the water, 

 Hie leaves become broad, rounder, and at the base more or less 

 emarginated. 



Plants that grow in elevated situations are the reverse, with re- 

 spect to the form of their leaves, of those that grow in water. 

 Their radical leaves are more or less intire : but the stem leaves, 

 the higher ihey rise, are always the more minutely divided. Exam- 

 ples of this we have in the Scabiosa Columbaria, Valeriana, &c. 



Plants in their wild state remain pretty constant in their appear- 

 ance, though they vary sometimes ; but these variations are incon- 

 siderable, in comparison of what tliey undergo when they become 

 objects of culture. It is remarkable, that both plants and animals 

 are no sooner domesticated than they begin to change their shape, 

 their colour and taste, Alpine plants, or those of the polar re- 

 gions, become, in vallies or gardens, very much larger; their leaves 

 increase in length and breadth, but their flowers grow smaller, or at 

 least do not increase. The plants of warm countries have so differ- 

 ent an appearance from that they have with us, lliat an inexperienced 

 botanist does not know them in their native places. How endless 

 are the varieties we find in our orchards and kitchen gardens. 



Now, whence comes the great number of distinct plants which 

 our earth produces! Were these ail created originally, or have new 

 species appeared since, in consequence of mixture with one ano- 

 ther? It is difficult to give a satisfactory answer to these questions. 

 Linnaeus and some other botanists have supposed, that nature origi- 

 nally formed nothing but genera, and that the species were produ- 

 ced afterwards by the mixture of these. This hypothesis, however, 

 seems untenable. In our days, we ought to see new species formed 

 by the mixture of various genera, and experiments would confirm 

 the fact. If it was possible for the infinite power which called every 

 thing into existence to create genera, why should it not also have 

 formed species 1 We find too much harmony, too much uniformity 

 in nature, and see so much consistency in the machinery of it, to 

 doubt that the wise Creator of the whole did not give at the begin- 

 ning to all organized bodies the forms we now see them in. Many 

 genera of plants, however, of which in some countries there are 

 very numerous species, may perhaps, by mixture, have produced a 

 new one. We find, for instance, at the Cape of Good Hope, of 



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