78 THE RUBBER INDUSTRY 



characteristics of soil, elevation above water-level, 

 exposure, and general surroundings. 



Throughout the rubber districts of the Lower 

 Amazon and those in the vicinity of the waterways 

 discharging into the delta, the average yield per tree is 

 less than in the other two sections of the Amazon 

 Valley, and a very rough estimate of the number of 

 labourers in comparison with the total output places 

 the weight of dry rubber per tree at slightly under 

 3 pounds. This is a very small return from fully 

 matured trees; but a great proportion of the trees in 

 these districts have been in tapping for half a century 

 past, and have been so seriously damaged by the care- 

 less use of the machadinho that the latex cells cannot 

 respond freely to the demands made upon them. In 

 the neighbourhood of the delta the conditions are 

 worse than on the upper reaches of the Rivers Tapajoz, 

 Xingu, and other tributaries ; while the yield in 

 these latter districts probably exceeds the average of 

 3 pounds per tree, the return on the islands and lower 

 sections of these rivers falls considerably short of that 

 figure. 



In the districts of the Madeira, the lower portions of the 

 Purus and Jurua, and the tributaries of these rivers, the 

 annual yield is higher than in the territories mentioned 

 in the last paragraph ; and on the same basis of calcula- 

 tion the average return works out approximately at 

 5 pounds per tree. Local report places the amount 

 at a much higher figure, but is coloured by the quantity 

 obtained from individual free-milking trees scattered 

 through the estradas. The check on exaggerated state- 

 ments is to take the total output and compare it with 



