OF THE ACCLIMATATION OF PLANTS. 



and accelerated by heat, humidity, and by a rich generous soil. Of course the 

 plants on the north side of a gravelly hill, whether indigenous or exotic, are 

 of a firmer texture and much more hardy than those on a rich southern slope. 

 This is the reason why plants in an irriguous valley are sooner destroyed by frost 

 than those on the bleak hill, and also why plants tenderly nursed up are sooner 

 damaged by a colder temperature than if reared in full air. The membranes in 

 the last case being more compact and juiceless ; in the other more attenuated 

 and succulent ; and according as these circumstances are more or less extreme, 

 the plant is more or less liable to be destroyed by frost. 



The action of frost upon vegetables shows itself in two ways ;. some plants 

 are only withered by it, but without any disruption of the membranes ; and on 

 the return of a thaw the leaves regain their rigidity and vigour as completely as 

 before. Other plants, from their natural or accidental succulence, delicacy of 

 membrane, and abundance of watery sap, are by the internal crystallization of 

 their juices rent into shreds and totally dismembered. 



Plants having a resinous sap seldom suffer from frost, because no crystallization 

 of such sap (to burst the tubular structure) takes place, and thus such plants 

 escape. 



The effect of extreme heat and moisture on vegetation excites to its utmost 

 expansion. Plants, natives of the temperate zones, if exposed to such excitement 

 for a longer time than their natural summer, become eventually quite exhausted, 

 and die in a few months. This happens to many European plants when carried 

 to India, such as the pear and apple trees ; and even the grape-vine lives in a 

 very weakly condition, and is but partially fruitful, unless grown on the highest 

 hills. 



These are a few of the circumstances which affect vegetation in the different 

 climates of our globe ; and the reason why the plants of one latitude do not 

 thrive in every other. 



If there be one circumstance which demands the admiration of the student of 

 vegetable nature more than another, it is the equal distribution of the most 

 useful plants over the face of the whole earth. A distribution which could only 

 be effected and planned by infinite power and wisdom ! Where vegetation is 

 deficient, there animals are mostly carnivorous ; and where vegetables abound, 

 roots, stems, leaves, and fruit, are, for the most part, the food of every living 

 creature. In those regions where vegetables are scanty, a short and hot summer 

 allows the industrious hind to cultivate a few of the tropical cereals for the 

 sustentation of himself and his fellows ; such as wheat, rye, and brank, these 

 serve them for bread corn, and grain, whence an ardent spirit may be obtained. 

 In the warmer parts of the temperate zones, and between the tropics, where 

 the field labourers and travellers are faint from the ardour of a vertical sun, 

 delicious and cooling fruits are found on almost every tree, and which are free 

 to every one without limit, save what a regard for health imposes. 



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