THE PARA RUBBER TREE 103 



The kernels of Para rubber seed have been shown by 

 examination at the Imperial Institute to contain about 

 45 per cent, of a drying oil which can be used for the same 

 purposes as linseed oil (see Imperial Institute Selected 

 Reports on Rubber and Gutta Percha, pp. 434-40). 



Distribution. — Hevea brasiliensis is very widely distri- 

 buted throughout the entii*e valley of the Amazon to the 

 south of the main stream, its habitat comprising portions 

 of Brazil, Bolivia, and Peru. It occurs on the low islands 

 and shores of the Amazon estuary, and on the alluvial 

 lands bordering the main stream and all its southern 

 tributaries. At the mouth of the Amazon the trees 

 grow above the limits of the tidal floods, but on the alluvial 

 lands of the lower rivers they a,re subject to annual in- 

 undations diu'ing the wet season. Hevea brasiliensis 

 also occiu-s in certain districts on the higher lands between 

 the rivers, and it was from such trees growing between 

 the Tapajoz and Madeira rivers that Wickham in 1876 

 collected the seeds which served to introduce the Para 

 tree into Ceylon and the Straits Settlements. Some doubt 

 has been expressed, however, as to whether the Hevea 

 trees growing on the higher lands are always the true H. 

 brasiliensis, and Ule is of opinion that the tree which occurs 

 in such situations in the Acre district is a distinct species. 

 According to Huber, the principal districts in the 

 Amazon valley where Hevea brasiliensis is abundant are 

 the forests situated on the shores and islands of the 

 estuary and along the banks of the rivers in the Staie of 

 Para ; the valleys of the Xingu, Tapajoz, and Madeira 

 rivers (the latter partly in Brazil and partly in Bolivia) ; 

 the Acre territory ; and the valleys of the rivers Purus, 

 Jurua, and Jutahy in Brazil, the Javary forming the 

 boundary between Brazil and Peru, and the Ucayali in 

 Peru. Brazil possesses large reserves of Para trees which 

 have not yet been exploited owing to difficulties of trans- 

 port, but several of these areas are now being opened up. 

 Climatic Conditions in Brazil. — The characteristic features 

 of the climate of i\\c Amazon valley are a uniform tempera- 

 ture and a considerable rainfall well distributed through- 

 out the year. On the lower river the mean annual tem- 

 perature lies between 76° and 81° F. and the annual 

 rainfall is usually from 80 to 120 in. In this region 

 tlie principal rainy season lasts from October to March, 



