THE TEOPICAL ZONE. 189 



feet, the mean temperature of which is from 81*5 to 86 

 Fahr., there are nevertheless some hardier species which 

 grow on the Andes "at a height varying from 6400 to 

 9600 feet, where the thermometer frequently sinks in the 

 night to 42*8 and 45'5 Fahr., and the mean temperature 

 is scarcely 57. They grow interspersed with Oaks (Quer- 

 cus Granatensis) , Nut-trees, and species of Podocarpus, trees 

 somewhat resembling the Yew. One of these is the beau- 

 tiful Wax-palm (Ceroxylon Andicola) before mentioned. 

 From these "kings among Grasses, whose physiognomy is 

 expressive of a grandeur of character which it is difficult 

 to describe in words," we must pass on to other natives of 

 the same warm regions. 



There are two plants, which may be named together here, 

 whose cultivation is extensively carried on within the tropics, 

 the Sugar-cane, namely, and the Cotton-plant, which will 

 now be still more familiar objects to us than heretofore, 

 though not altogether new acquaintances, both having been 

 recently met with in extratropical countries. 



Amongst the trees (or bushes, for their size varies) the 

 Mimosas must not be forgotten, which reach their greatest 

 perfection in tropical countries. Hot, damp tracts of land 

 are sometimes quite covered with them ; their spreading 



