OF RESTING. 319 



which is analogous to its winter state. For many 

 parts of gardening, especially what relates to forcing 

 and the management of exotic plants, this is a subject 

 of the first importance. 



If we look over the different climates of the world, 

 we shall find that in each there are a season of growth, 

 and a season in which vegetation is more or less sus- 

 pended ; and that these periodically alternate, with 

 the same regularity as our summer and winter. I do 

 not know that there is in nature any exception to this 

 rule: for, even in the Tierra templada of Mexico, 

 where it is said that, at the height of 4000 to 5000 

 feet, there constantly reigns the genial climate of 

 spring, which does not vary more than 8° or 9°, in- 

 tense heat and excessive cold being alike imknown, 

 and the mean temperature varying from 68° to 70°, 

 we cannot suppose that, even in that favoured region, 

 a season of repose is wanting ; for it is difficult to con- 

 ceive how plants can exist, any more than animals, in 

 a state of incessant excitement. Indeed, it is pretty 

 evident that these countries have a period when vege- 

 tation ceases ; for Xalapa belongs to the Tierra tem- 

 plada, and we know that the Ipomoea purga, an inha- 

 bitant of its woods, dies down annually like our own 

 Convolvuli. 



But, although all plants have naturally a season 

 of repose, their winter is not in all cases cold. In the 

 tropics it is marked by coolness and dryness, while 

 the summer is rainy and very hot ; and in extra-tro- 

 pical countries the two seasons vary in their charac- 

 ter according to latitude and local circumstances. 



