Chap. I. THE CHINCHONA REGION. 11 



equable temperature, on the slopes and in the valleys and 

 ravines of the mountains, surrounded by the most majestic 

 scenery, never descending below an elevation of 2500, and 

 ascending as high as 9000 feet above the sea. ^Yithin these 

 limits their usual companions are tree ferns, melastomaceae, 

 arborescent passion-flowers, and allied genera of chinchonaceous 

 plants. Below them are the forests abounding in palms and 

 bamboos, above their highest limits are a few lowly Alpine 

 shrubs. But within this wide zone grow many species of 

 chinchonae, each within its own narrower belt as regards 

 elevation above the sea, some yielding the inestimable bark, 

 and others commercially wortliless. And the species of chin- 

 chonas, in then- native forests, are not only divided from each 

 other by zones as regards height above the sea, but also by 

 parallels of latitude. In Bolivia and Caravaya, for instance, 

 the valuable C. Calimya abounds, but it is never found 

 nearer the equator than 12° S. Between that parallel and 

 1 0" S. the forests are for the most part occupied by worthless 

 species, while in Northern Peru the important grey barks of 

 commerce are found. In each of these latitudinal regions the 

 diiferent species are again divided by belts of altitude. Yet 

 this confinement within zones of latitude and altitude is 

 not a constant ride ; for several of the hardier and stronger 

 species have a wider range ; while the more sensitive, and 

 these are usually the most precious kinds, are close prisoners 

 within their allotted zones, and never pass more than a 

 hundi'ed yards beyond them. All the species are, of course, 

 affected by local circumstances, which more or less modify 

 the positions of their zones, as regards altitude. 



Thus, to give a geographical summary of the chinchona I 

 region, beginning from the south, it commences in the 

 Bolivian province of Coehabamba in 19° S., passes through 

 the yungus of La Paz, Larecaja, Caupolican, and Munecas, 

 into the Peruvian province of Caravaya ; thence through 



