114 ON THE NATURALISATION 



Emily. I should have imagined that the quality of 

 the soil and the quantity of water would have been of 

 still greater consequence than the temperature. 



Mrs. B. When we wish to naturalise a foreign plant, 

 art may do much in rendering the soil analogous to that 

 in which it originally grew, in affording it a due quanti- 

 ty of water, in sheltering it from, or exposing it to the 

 light. The nature of the air varies very little in any lat- 

 itude, but its temperature most remarkably ; and over 

 this art has little or no control. 



Caroline, You forget our hothouses, Mrs. B., where 

 we produce whatever temperature we choose. 



Mrs. B. True ; but the plant cultivated, or I should 

 rather say forced, in such an artificial atmosphere remains 

 a foreigner, and does not become *a naturalised subject 

 of the vegetable realm. 



If you compare the mean temperatures of different 

 countries, you will be surprised to find how much more 

 nearly they approximate to equality than you would at 

 first imagine. For instance, those of England and of 

 Switzerland do not vary above two or three degrees ; 

 yet they frequently will not admit of the cultivation of 

 the same plants. In Switzerland it is hotter in summer 

 than in England, owing to the latitude ; whilst its local 

 elevation, and the vicinity of mountains covered with 

 snow, renders it colder in winter. The more equable 

 temperature of England, throughout the year, enables eve- 

 ry species of laurel, and even Rhododendrons, to support 

 the winter with impunity. In Switzerland the common 

 laurel, if it escape being frozen, suffers so much as great- 

 ly to injure its vigor and its beauty : the contrast of a 

 strong vegetation in summer, suddenly checked by the 

 severity of winter, ill accords with its nature. The lau- 

 rustinus and the Portugal laurel are unknown in Switzer- 

 land, except as greenhouse plants ; whilst, on the other 

 hand, the fruit of the vine, which we can but imperfectly 

 ripen in England, in Switzerland affords aluxuriant vintage. 



640. What is it said that art may do for the soil in reference to for- 

 eign plants'? 641 . What does Mrs. B. say of hothouse plants'? 642. 

 -With what does she say one will be surprised'? 643. What com- 

 parison is made between the temperature of England and Switzerland'? 

 644. What is said of the growth of laurel and Rhododendrons, in these two 

 countries'? 645, And of the lauristinus, the Portugal laurel, and the 

 vine 1 ? 



