122 AGRICULTURE IN THE TROPICS [PT. II 



of the tree, where it dried. In this way 13 J Ibs. of dry rubber 

 were obtained in nine years, or an average of 1 J Ibs. a year ; 

 the tree was ten years old when first tapped. At the then 

 price of rubber a yield like this, only obtained after waiting 

 ten years, was hardly sufficient to tempt anyone into the 

 cultivation, and in this condition the question remained until 

 1897, when further experiments were made, and the im- 

 portant discovery, or rather rediscovery the facts being well 

 known to the natives of the Amazon valley of the "wound- 

 response" was made by the writer. In the following two years 

 this was fully worked out by Mr John Parkin, then Scientific 

 Assistant in the Royal Botanic Gardens of Ceylon, and an 

 abstract of some of his results may be of interest. In general 

 it is found that if a small area of the bark be tapped a second 

 time within a short period, the amount of latex that flows 

 from it is larger than at the first tapping, and this increase 

 may even go on for a considerable time. Thus from 40 in- 

 cisions made on March 25, 1899, only 60 c.c. of latex were 

 obtained; on March 30, from a further 40 close to the old, 

 105 c.c. flowed ; on April 6, 220 c.c., while in the thirteenth 

 tapping on June 1, 328 c.c. were obtained, and on June 6, 

 449 c.c., or nearly eight times the amount realised by the first 

 tapping. These were no doubt exceptional figures, but in 

 general his work showed that about three times as much 

 milk would be obtained later, as at the first tapping. On the 

 basis of these and other experiments, results were published, 

 showing that there was a possibility of a profit of about 

 27 % after the tenth year, and as seed was then beginning 

 to be available in some quantity, people began to take up 

 the planting of rubber, and the area under this cultivation 

 has increased from year to year. In 1907 rubber planting was 

 the main topic of conversation in tropical planting circles, and 

 a great "boom" went on in it. The earlier pioneers of rubber 

 cultivation made much larger profits than the 27 % anticipated, 

 because the trees proved to give a yield at five to seven years 

 old instead of ten, the yield was larger, and the price of rubber 

 was very high during the last few years. When this was 

 realised in Europe, there was a "boom" in rubber upon the 



