Gums, Resins, 



388 



[May, 1910. 



After the lapse of two days, incisions 

 were made near the wound and also on 

 parts of the trunk at the same level 

 farthest away from, i.e., opposite, the 

 injury. Fully double the quantity of 

 latex was obtained from the outs near 

 the wound, as compared with that 

 yielded by those incisions made opposite. 



Attention was then directed to the 

 time-interval necessary in order to 

 render this response recognisable. After 

 twelve hours no difference was observed 

 between the volume of latex yielded by 

 the two classes of incisions. Sometimes 

 after twenty-four hours and generally 

 after two days, the effect of woundiug 

 on the yield, however, was marked. 

 Apparently the drier the soil the longer 

 the time required for the response to 

 appear. The experience of planters and 

 others since has shown that two days is, 

 as a rule, the best interval between 

 successive tappings, but some estates tap 

 every day with good returns. 



The following table gives in concise 

 form the results of a somewhat elaborate 

 experiment conducted at Peradeniya 

 from March to June, 1899.* Four trees 

 were employed, and a horizontal row of 

 ten similar incisions made per tree per 

 tapping. Each fresh row of incisions 

 was made near those of the preceding 

 tapping, in order that the wound- 

 response might take effect. The in- 

 terval between tappings was usually 

 five days. A less allowance would moat 

 likely have made the experiment still 

 more striking. 



Volume of latex Volume of 

 in cubic Latex in 



centimeters. cubic cent. 



1st tapping ... 61.0 8th tapping ... 253-0 



2nd 105*5 9th „ ... 216-5 



3rd „ ... 220-0 10th „ .. 275-0 



4th ,, .. 208-5 11th „ ... 255 



6th „ ... 255-5 12th „ ... 262-0 



6th „ 290-0 13th „ ... 328 



7th ,, ., 276-0 14th „ ... 449-0 



This experiment brought out the effect 

 of wounding on the flow of latex in a 

 still more favourable light ; and con- 

 sidering that at the fourteenth tapping, 

 when the experiment had to be brought 

 to a conclusion, the volume was the 

 largest collected, it would appear that 

 the limit to the full advantage to be 

 gained from wound-response had not yet 

 been reached. 



From a practical point of view this 

 experiment is defective in that no 

 estimations were made as to the percent- 

 age of caoutchouc in the latex from the 

 successive tappings. A large flow might 



* S. Arden, Report on Hevea brasHknsis in the 

 Malay Peninsula^ 1902 p. 15, 



mean a thin milk, yielding little solid 

 rubber. Stanley Arden's work in the 

 Malay States has supplied in some 

 measure the deficiency. His results, 

 published in 1902, have proved that the 

 weight of caoutchouc itself is increased 

 by the wound-response, and this incre- 

 ment is maintained or further augmented 

 for a number of tappings. The following 

 figures referred to one of his experi- 

 ments, in which ten trees were tapped 

 every day for a fortnight. 





Wet rubber. 





Wet rubber. 





in oz. 





in oz, 



1st tapping 



... 6J 



8th tapping 



... 31| 



2nd „ 



... 115 



9th ,, 



... 29 



3rd 



... 174 



10th „ 



... 301 



4th „ 



... 23| 



11th „ 



... 31i 



5th ,, 



... 26g 



12th , 



... 29g 



6th ,, 



... 26| 



13th ,, 



... 30| 



7th , 



.. 231 



11th ,, 



... 33| 



Here, as in the Ceylon experiment, the 

 yield per tapping has been well main- 

 tained throughout; and at the fourteenth 

 and last tapping instead of any diminu- 

 tion in yield, there is a slight increase, 

 showing that the experiment could have 

 been continued longer with profitable 

 results. 



The demonstration of wound-response, 

 therefore, placed Hevea in a much more 

 favourable position as a rubber pro- 

 ducer, stimulating its cultivation. Be- 

 fore the discovery of this peculiarity; 

 Hevea as a latex yielder in Ceylon did 

 not look at all exceptional — in fact, it 

 appeared less promising than Castilloa. 

 From similar incisions made in untap- 

 ped trunks of these two trees much 

 more latex flows from Castilloa than 

 from Hevea — roughly five to six times as 

 much. But if after the lapse of one or 

 two days fresh incisions are made in 

 the trees quite near the old ones, it will 

 be found that from the Castilloa no 

 latex, or very little, oozes out, while 

 from the Hevea about double the volume 

 given by the first wounds can be collect- 

 ed, aud further, this tree will continue 

 giving this and even larger quantities 

 for some time to come. Consequently a 

 very much greater weight of rubber will 

 be obtained in a year from a tree 

 of Hevea thai: from one of Castilloa of 

 a similar size. The yields from estates 

 planted with these two trees bear this 

 out in a striking manner. 



The planting of Castilloa in Mexico, as 

 already mentioned, commenced a year 

 or two in advance of that of Hevea in 

 the East. Wound-respouse not being 

 then known, the former seemed the 

 more promising tree, as it yielded its 

 latex with greater ease. At the present 

 time, however, little is heard of Castilloa 

 plantation rubber, while that of Hevea, 



