RUBBER PLANTING 131 



labour as compared with good paring. From such a 

 discussion we may hope to arrive at an understanding 

 of the features which should characterise an ideal system 

 of pricking. 



The method of incision was employed by Trimen 

 in Ceylon prior to 1888, but the precise method adopted 

 was not exactly specified. Among the earliest methods 

 of incision practised upon planted trees, of which we 

 have a satisfactory record, was the one employed by 

 Parkin in experiments at Henaratgoda. Parkin's 

 method, which was based on those used in the col- 

 lection of wild rubber in Brazil, was to make V-shaped 

 cuts in the bark by the aid of a hammer and chisel. 

 With this method two definite defects are associated 

 in practice. A separate collecting cup is required for 

 each V, whilst the surface of the tree becomes rough 

 and lumpy owing to the irregular renewal thus induced, 

 until further tapping becomes a difficult matter. More- 

 over, except in the case of old trees with very thick bark, 

 it is impossible to avoid more or less extensive injury 

 to the cambium. The method is quite unsuitable for 

 young trees. 



The fact is that no method of large incisions truly 

 conforms to Wright's definition of good tapping, since 

 such incisions entail the destruction, if not the removal, 

 of a considerable mass of living cortex. This destruc- 

 tion goes much deeper than that caused by careful 

 paring, and often involves the cambium itself. On the 

 other hand, a small clean prick, such as may be made 



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