June, 1912.] 



489 



Saps and Exudations. 



nation of the problems of its production. 

 The apprehension that one day the 

 natural supply of the Brazilian forests 

 might fail and the hope of competing in 

 the sale of this valuable product have 

 resulted in natural resources being 

 sought for everywhere in the forests of 

 Asia and Africa, and have caused the 

 question to be studied from the point of 

 view of cultivation, turning to account 

 the climate and soil of the tropical 

 countries under the dominion of the 

 Great European Nations. The same 

 reasons, however, at the same time urged 

 industry and science towards a solution 

 of that very problem by entirely diver- 

 gent paths, viz. the regeneration of the 

 rubber of used articles, the creation of 

 rubber substitutes, and finally one of the 

 most attractive and difficult problems, 

 the chemical synthesis of rubber. And 

 indeed the possibility of increasing the 

 production and limiting the causes of 

 waste and loss of the raw material seems 

 to set at rest all fears as to a shortage of 

 the commodity, although consumption is 

 still increasing. The natural reserves 

 are for that matter sufficient in number 

 and in wealth to meet the most enor- 

 mous demands, pending other resources 

 being added thereto in order to regulate 

 and lower the price of the product. 



The world's consumption of rubber is 

 calculated by M. A, Dubosc as being, for 

 1911, 85,000 tons, with a co-efficient of 

 increase of 8% per annum, which would 

 raise the total world's consumption to 

 180,000 tons about 1920, and the business 

 turnover calculated by Sir H. Blake at 

 1,100 million per year, would attain to 

 more than 2% thousand million francs. 



Of the whole of this enormous con- 

 sumption, the greatest part is supplied 

 by Brazil with its wild rubber, Para, 

 which also ranks highest in point of 

 quality. In 1910 Brazil is said to have 

 produced 38,000 tons of Para, that is, one 

 half of the world's consumption. 



Each great producing region appears 

 to have its special rubber plant. In 

 Brazil the area of Amazonas, which is 

 the principal producing centre, amounts 

 to nearly 6£ million sq. kilometers 

 62 



(2,509,000 sq. miles) i.e„ 12 times the area 

 of Prance. In all parts of this State 

 there are found one or another of the 

 varieties of Hevea or Castilloa but especi- 

 ally that wonderful tree, Hevea Brasi- 

 liensis, which, with well-conducted tap- 

 pings can when mature, at about 35 

 years, yield up to 12 kgs (25 • 4 lb.) of 

 rubber. The number of trees standing 

 in the two States of Para and Amazonas 

 is estimated at 200 million. In the State 

 of Amazonas, the field of working of the 

 natural " seringaes " (rubber estates) is 

 growing day by day, in consequence of 

 exploration being carried to the very 

 remotest ramifications of the great 

 rivers, which are the confluents of the 

 Amazon ; unfortunately the impossi- 

 bility, almost, of transport make the cost 

 price unremunerative. Still the reserves 

 of rubber ripe for tapping in the Ama- 

 zonian region are not limited to the 

 great number of Hevea Braziliensis form- 

 ing the principal wealth of that country. 

 They are also formed by other natural 

 rubber bearing species of appreciable 

 value, at least equal to that of some 

 famous plants of other countries. 



While in the Southern part of the 

 basin of the Amazon, Hevea brasili'.nsis 

 occupies the leading place, Hevea bentha- 

 miana supplies the best quality rubber 

 north of the Amazon, especially in the 

 basin of the Rio Negro. 



On the Rio Negro there are, however, 

 a certain number of other species of 

 Hevea, the economic value of which 

 is not well-known as yet, such as Hevea 

 lutce, apiculata, rigidifolia, minor, etc. 



Hevea guyauensis and some allied 

 species supply what is called in Brazil 

 the " Borraeha f raca " or poor rubber. 



The genus Micranda has not been 

 studied much as yet from the point of 

 view of the value of its product, but 

 according to Ule, a species desseminated 

 in the Upper Basin of the Amazon, M. 

 siphonoides yields a good product. Of 

 the genus Sapium, represented in the 

 region by at least a dozen tree, only 

 <S. Taburi is known as supplying a good 

 quality rubber. This tree is fairly fre- 

 quent in the alluvial soils of the Amazon 



