292 POPULAR GEOGRAPHY OF PLANTS. 



There is reason to fear, as it occupies a very limited vertical 

 region on the Andes, that as the life of the tree is neces- 

 sarily sacrificed in taking the bark, the true Cinchona may 

 become extinct within the next fifty years. 



The upper limit of this narrow region is coincident with 

 that of the high forest vegetation ; the lower one is a little 

 above the level of the plain ; its extreme limits extend from 

 about 3937 to 10,728 feet, the average height being some- 

 where between 5249 and 7874 feet. The mean tempe- 

 rature of this important forest region varies from 60 to 

 68 Fahr. 



As a counterbalance to these narrow vertical limits, the 

 horizontal range of the Cinchona region, which is chiefly on 

 the eastern side of the inner chain of the Andes, may be 

 traced like a narrow belt, more or less winding, from just 

 beyond 10 north latitude to 19 south latitude; thus it 

 extends over 29 of latitude. Near Loxa, at 4 south lati- 

 tude, where the inner chain of the Andes disappears, the 

 Cinchona approaches towards the sea.* 



* The facts connected with the Cinchona, and most of those about the 

 Andes, are taken from Dr. WeddelTs ' Histoire Naturelle des Quinquinas.' 

 The accompanying figure of the Cinchona, stripped of its bark, is also bor- 

 rowed from this source. 



