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that no estimations were made as to the percentage of caoutchouc 

 in the latex from the successive tappings. A large flow might 

 mean a thin milk, yielding little solid rubber. Stanley Arden's 

 work in the Malay States has supplied in some measure 

 the deficiency. His results, published in 1902, have proved 

 that the weight of caoutchouc itself is increased by the 

 wound-response, and this increment is maintained or further 

 augmented for a number of tappings. The following figures 

 refer to one of his experiments, 1 in which ten trees were tapped 

 every day for a fortnight : 



Here, as in the Ceylon experiment, the yield per tapping has 

 been well maintained throughout ; and at the fourteenth and 

 last tapping, instead of any diminution in yield, there is a slight 

 increase, showing that the experiment could have been continued 

 longer with profitable results. 



The demonstration of wound-response, therefore, placed 

 Hevea in a much more favourable position as a rubber producer, 

 stimulating its cultivation. Before the discovery of this peculi- 

 arity, Hevea as a latex yielder in Ceylon did not look at all 

 exceptional — in fact, it appeared less promising than Castilloa. 

 From similar incisions made in untapped trunks of these two 

 trees much more latex flows from Castilloa than from Hevea 

 — roughly five to six times as much. But if after the lapse of 

 one or two days fresh incisions are made in the trees quite 

 near the old ones, it will be found that from the Castilloa no 

 latex, or very little, oozes out, while from the Hevea about 

 double the volume given by the first wounds can be collected, 

 and further, this tree will continue giving this and even 

 larger quantities for some time to come. Consequently a 

 very much greater weight of rubber will be obtained in a 

 year from a tree of Hevea than from one of Castilloa of 



1 S. Arden, Report on Hevea brasiliensis in the Malay Peninsula, 1902, p. 15. 



