210 



[September, 1908. 



GUMS, RESINS, SAPS AND EXUDATIONS. 



TAPPING EXPERIMENTS ON RAM- 

 BONG AND PARA. 



Professor Dr. A. Weberbauer records 

 in the last December number of the 

 "Tropenflauzer " some interesting experi- 

 ments he made in Camernn on the tap- 

 ping of certain species of rubber-bear- 

 ing plants. We abstract his remarks on 

 Ficus elastica (Rambong) and Hevea 

 braziliensis (Para). 



In tapping Ficus elastica he used the 

 ordinary tapping knife ("die Kaeufii- 

 chen Kautschukmesser "). In the outer 

 layer of bark, which contains little or no 

 latex, a groove was cut to the depth at 

 which the first drops of latex show them- 

 selves, then with an ordinary penknife a 

 deep cut was made in the bottom of the 

 groove. The author claims that wounds 

 in the cambium, which cannot always be 

 avoided, will heal more quickly, if caused 

 by the sharp pocket knife than by the 

 ordinary coarser tapping knife. 



The weights given are those of well- 

 dried rubber. 



In the first experiment two trees with 

 stems of about equal girth were taken. 



In (a) a cut of 16 centimetres (about Qh 

 inches) was made in a sloping direction. 



In (b) the cut was 22 centimetres (about 

 8| inches) and parallel with the axis of 

 the stem, that is vertical in the case of 

 an upright growing tree. The yield 

 from (a) was 2'1 grams (1000 grams = 2i 

 lbs.) from (b) 1'2 gram; so that the 

 sloping cut, though shurter than the 

 other, yielded nearly twice as much 

 rubber. 



In another experiment six cuts were 

 made on the same branch and on succeed- 

 ing days, except that a clear day inter- 

 vened between the second and third. 

 All cuts were made at right angles to 

 the long axis of the branch, which grew 

 horizontally. The time of day, 9 to 12 

 o'clock, was much the same in each case, 

 and so was the weather. The first cut 

 yielded 1247 grams ; the second, close to 

 but behind No. 1 on the same side of the 

 stem, gave 0*87 grams ; the third, on the 

 same side as No. 2 and about 4 inches 

 distant from it, yielded 2'03 grams ; the 

 fourth was on the same side as No. 3 and 

 distant about 8 inches, the yield was 2 25 

 grams. The fifth was on the opposite 

 side to the previous ones and lay under 

 the first : it yielded 8-80 grams. The 

 sixth was on the same side of the stem as 

 the fifth but 16 inches distant from it : 

 yield 226 grams. 



The first cut gave more than double as 

 much rubber as the three others together 

 which were on the same side of the 

 branch. The farther the cuts are from 

 each other the greater is the yield. On 

 the opposite side of the stem, the fifth 

 cut gave nearly four times as much latex 

 as the sixth, though the distance 

 between them was relatively large. 

 Therefore if Ficus elastica is tapped 

 with sloping cuts, and if a good number 

 of these are made in a short time, they 

 should, if they lie on the same side of a 

 stem or a branch, be made considerable 

 distances apart, otherwise there is only 

 a useless injuring of the tree. In his 

 fifth and sixth experiments the author 

 found that if the time between two 

 tappings is lengthened (to three weeks or 

 a month) the distance between the cuts 

 may be lessened. It would, perhaps, 

 have been more valuable if more trees 

 had been tapped in each experiment. 



The author made & number of experi- 

 ments on Hevea braziliensis. He applied 

 the spiral and the herringbone methods, 

 and short sloping separated cuts, but 

 none vertical ; his object was not so 

 much to compare different methods of 

 tapping as to see whether Para yielded 

 paying quantities of latex in Camerun, 

 which has been doubted. 



The sloping cuts gave somewhat the 

 best results. The method was as 

 follows : — The tapping-knife and pen- 

 knife were used exactly as in the Ram- 

 bong experiments. 



Six sloping cuts, each 4 inches long, 

 were made at equal distances apart (and 

 presumably at the same level) round 

 the stem. Every cut was parallel with 

 and 2 inches from that of the previous 

 day, so that after 28 days the surface of 

 the tree exhibited six vertical rows of 

 sloping cuts, 28 parallel cuts in each row, 

 and the rows separated by six stripes of 

 untouched bark. The author does not 

 state the width of each groove. Not 

 much can be deduced from the figures 

 given. Only three trees, one of each 

 method, were experimented on, and the 

 periods during which they were tapped 

 do not agree. 



There are things against the practica- 

 bility of the separated sloping cut. It 

 would be interesting to know if less 

 bark is used up, and if it renews more 

 quickly than is the case with the almost 

 universal herringbone method. — Agricul- 

 tural\Bulletin of the Straits and Feder- 

 ated Malay States, No. 4, April, 1908, 

 Vol. VI. 



