646 RUBBER 



The Distance between the Cuts. 



The cuts of the herring-bone have usually been made 

 i ft. apart, without any special reason. Probably the 

 most generally accepted idea in tfce earlier days of tap- 

 ping was that the cuts should be placed so far apart that 

 the bark between them was excised completely in one 

 year. Experiments with different distances are entirely 

 wanting, but they are not now required. In a Peradeniya 

 experiment, which has been in progress for eighteen 

 months, one set of trees is tapped with four cuts i ft. 

 apart, another with two cuts i ft. apart, and a third with 

 two cuts 2 ft. apart, in all cases alternate day tapping 

 on one-third circumference; the two cuts 2 ft. apart have 

 up to the present given the best yield. But from physio- 

 logical investigations now in progress it would appear 

 that prolonged continuous tapping on the same area is 

 not to be recommended. In that respect the longer 

 distance between the cuts is a disadvantage. 



It may be noted that the tapping with two cuts 2 ft. 

 apart, the lowest being 2 ft. from the base of the tree, 

 yielded more than tapping with two cuts i ft. apart, the 

 lowest in the latter case being only i ft. from the base. 

 This conflicts with the prevalent idea that the lower the 

 cut the greater the yield. That is true for a single tap- 

 ping, but in prolonged tapping there would appear to 

 be little difference in the yield whatever the height of 

 the cut, provided it is within 3 ft. of the ground; 26 in. 

 is now a common height for the lowest cut. 



The Number of Cuts. 



In 1905 it was customary to tap the lowest 6 ft. of 

 the stem with a full or half herring-bone of six cuts 

 i ft. apart. It was soon evident that the yields of these 

 cuts were unequal, and that some of them occasionally 

 " ran dry." But it was a long time before observation 

 influenced practice. The only record on this point is one 

 by Lock, who found that when the bark between the cuts 

 was nearly exhausted the lowest cut yielded as much latex 

 as all the other five put together. In six months' tap- 

 ping the yield of the latex from the lowest cut was two 



