THE PRINCIPAL RUBBER DISTRICTS 35 



and it is the predominant species of rubber-tree 

 throughout these regions. Castilloa also flourishes at 

 the higher elevations, but the ruthless destruction of 

 the trees during recent years by the caucho collectors is 

 a serious menace to its future profitable exploitation. 



In the rubber-producing districts of Bolivia in the 

 neighbourhood of the River Beni and the adjacent 

 waterways, a considerable proportion of the collectors 

 is recruited from the domesticated Indian population 

 who have been settled in this part of the country since 

 the Inca period. Nowhere else, however, in the Amazon 

 Valley is there any regular supply of Indian labourers, 

 all efforts to civilize the various nomad tribes having 

 proved futile in Brazilian and Peruvian territory. In 

 these circumstances the exploitation of the rubber-trees 

 has been carried on almost entirely by imported work- 

 men, and the expense of recruiting these immigrants in 

 Ceara and elsewhere, and transporting them over the 

 2,000 miles intervening between this section of country 

 and the Atlantic seaboard, has been one of the most 

 formidable obstacles in the way of the expansion of the 

 industry in the past, and promises to be a very serious 

 problem in the future. 



With few exceptions, the buildings erected in the 

 third section of the Amazon Valley are of a temporary 

 character, and constructed of timber or reeds, with floors 

 raised on piles above the level of the annual inunda- 

 tions. It is a remarkable fact that, although high and dry 

 land is very frequently available within a few hundred 

 yards from the banks of the rivers, the general custom 

 is to locate the homesteads as close as possible to the 

 water, the only explanation being that this habit saves 



