PARA RUBBER. 95 



knife, and in an interval of 4£ months the width of bark tissues re- 

 moved along each line is only H to 2 inches. The results show that 

 by tapping on 37 occasions a total of 50§ lb. of dry rubber can be 

 obtained from 25 such trees. 



The following shows some of the yields obtained by tapping on the 

 long spiral system at Henaratgoda ; each tree was tapped from the 

 base to a height of 5 or 6 feet during a period of about 4J months : — 

 Lono Spipal Tapping Experiments. 



Number of 



times tapped. 



37 

 L 1 2 



56 



18 

 100 



Experiments at Henaratgoda. 



The objects of the experiments at Henaratgoda are numerous and 

 have been made public on several occasions. One of them is 

 concerned with the yield of dry rubber obtainable by different systems 

 of tapping, and is of particular interest to those persons having 

 rubber trees in bearing. A plantation of 75 rubber trees, 15 to 20 

 years old, was selected (see Plate 1, Series A) and 25 trees in each 

 of three groups were marked out and tapped on the (a) full spiral, 

 (b) half-spiral, and (c) the full herring-bone systems. Tapping was 

 commenced on the 26th September, 1905, and continued until 

 the 13th of February, 1906, the latter being the period when most 

 of the trees were undergoing their change of leaf. 



It was impossible to obtain exact equality in all the physical 

 conditions, and it is beyond the power of any one to calculate the 

 individual potentialities of the selected trees ; nevertheless, the 

 following details will serve to indicate the results which may be 

 obtained from such trees under conditions similar to those prevailing 

 at the time of the experiments. 



Comparison of Yields by different Systems of Tapping. 



