ON PRODUCING NEW AND EARLY FRUITS, 173 



If two plants of the vine or other tree of similar habits, or even if 

 obtained from cuttings of the same tree, were placed to vegetate, during 

 several successive seasons, in very different climates : if the one were 

 planted on the banks of the Rhine, and the other on those of the Nile, 

 each would adapt its habits to the climate in which it were placed ; and 

 if both were subsequently brought, in early spring, into a climate similar 

 to that of Italy, the plant which had adapted its habits to a cold climate 

 would instantly vegetate, whilst the other would remain perfectly torpid. 

 Precisely the same thing occurs in the hot-houses of this country, where 

 a plant accustomed to the temperature of the open air will vegetate 

 strongly in December, whilst another plant of the same species, and 

 sprung from a cutting of the same original stock, but habituated to the 

 temperature of a stove, remains apparently lifeless. It appears, there- 

 fore, that the powers of vegetable life, in plants habituated to cold 

 climates, are more easily brought into action than in those of hot 

 climates ; or, in other words, that the plants of cold climates, are most 

 exciteable: and as every quality in plants becomes hereditary, when 

 the causes which first gave existence to those qualities continue to 

 operate; it follows that their seedling offspring have a constant ten- 

 dency to adapt their habits to any climate in which art or accident 

 places them. 



But the influence of climate on the habits of plants, will depend less 

 on the aggregate quantity of heat in each climate, than on the distribution 

 of it in the different seasons of the year. The aggregate temperature 

 of England, and of those parts of the Russian Empire that are 

 under the same parallels of latitude, probably does not differ very 

 considerably ; but, in the latter, the summers are extremely hot, and 

 the winters intensely cold ; and the changes of temperature between the 

 different seasons are sudden and violent. In the spring great degrees of 

 heat suddenly operate on plants which have been long exposed to intense 

 cold, and in which excitability has accumulated during a long period of 

 almost total inaction : and the progress of vegetation is in consequence 

 extremely rapid. In the climate of England, the spring, on the contrary, 

 advances with slow and irregular steps, and only very moderate and 

 slowly- increasing degrees of heat act on plants in which the powers of 

 life have scarcely in any period of the preceding winter been totally 

 inactive. The crab is a native of both countries, and has adapted 

 alike its habits to both ; the Siberian variety introduced into the 

 climate of England, retains its habits, expands its leaves, and blossoms 

 on the first approach of spring, and vegetates strongly in the same 



