96 PARA RUBBER. 



Spiral and Herring-bone Tapping compared. 



It is probably unwise to draw final conclusions from the above 

 experiments, as the period occupied for the whole of the work lasted 

 only about five months and the trees were 15 to 20 years old at the 

 time of the experiment. But care was exercised to equalize, as far 

 as possible, the physical conditions in the three sections and to avoid 

 erroneous deductions being made. A synoptical statement of the 

 significance of the above table is here given. 



In the first case it is obvious that the full spiral system necessitates 

 the stripping of the cortex or bark at the quickest rate, and the half- 

 spiral at the minimum rate. 



The largest yield per group of 25 trees has been obtained from the 

 full spiral system, the next best from the full herring-bone, and the 

 ■poorest yield from the half-spiral system of tapping. This is only 

 what may be expected when one realises that the bark removed in 

 the full spiral, full herring-bone, and half-spiral systems was in 

 the ratio of 12 : 7 : 5, respectively. It seems reasonable to con- 

 clude that since the above results show that the maximum 

 quantity of rubber per tree has been obtained from the full spiral 

 system, such a system is to be recommended where it is expedient 

 that the rubber should be placed on the market as quickly as 

 possible irrespective of the effect on the trees. The adoption of this 

 system removes the maximum quantity of bark, in a given time, 

 and it is, therefore, the best one to adopt in thinning-out estates 

 which are too thickly planted. 



On the other hand, it appears that the maximum quantity 

 of rubber for equal areas of bark has been obtained from the half- 

 spiral system, and, therefore, that this system is not only the 

 least harmful, but is the most economical, and is one which, on a 

 permanent estate, will give the best yield from the available tap- 

 ping area. 



It should, however, be pointed out that in these experiments 

 the different systems have been carried out in such a manner that the 

 paring operations have only removed from 1| to 2|- inches of cortex, 

 along each incision, in five months. The tapping fines were 

 originally 12 inches apart, so that the whole of the area prepared 

 for tapping will only be worked through once in about two to three 

 years. If the Para rubber tree is not too seriously injured by 

 complete cortical stripping once every three years, it seems likely 

 that the full spiral system of tapping, though the least economical, 

 is one which will be largely adopted in the future on account of 

 the large yields obtainable thereby. 



Results of High Tapping at Henaratgoda. 



The foregoing results were obtained by tapping selected sides of 

 trees from the base to five or six feet from the ground. In addition 



