RUBBER PLANTING 59 



Further details with regard to tapping will be found 

 in Chapter VI ; but it may be pointed out here that the 

 method described is known as an excision method, as 

 opposed to methods of incision in which the bark is 

 merely pricked with a pointed instrument or gashed 

 with a hatchet or chisel. The latter is the method 

 generally employed in collecting wild rubber, whereas 

 on plantations excision is the rule. 



Wound Response. 



If a tree of Castilloa or Funtumia is tapped, and the 

 wounds are reopened after an interval of a few days, or 

 if the bark is again tapped after a short interval in the 

 neighbourhood of the original cuts, little or no latex is 

 obtained at the second tapping. The bark is milked 

 almost dry at a single operation, and the latex tubes 

 are not completely refilled for several months 1 . In 

 the case of Hevea and Manihot, on the other hand, 

 a good yield is again obtained after an interval of only 

 a single day. These facts have long been known to the 

 collectors of wild rubber. The Hevea trees in the forests 

 of Brazil are tapped repeatedly during a single season, 



method was given up about the middle of 1911, owing to the accumulation 

 of evidence that the use of the pricker led to damage of the trees. The 

 result of subsequent tapping in which the paring knife only was used, con- 

 firmed this impression and led to a general increase of yield. 



The use of the pricker may be regarded as having accentuated the 

 damage done to the bark of the trees tapped at shorter intervals. 



1 If indeed they ever recover. It is equally likely that much of the 

 latex obtained at later tappings is derived from new latex tubes budded off 

 from the old ones. 



