THE PRINCIPLES OF HEVEA TAPPING, AS 

 DETERMINED BY EXPERIMENT. 



By T. FETCH, B.A., B.Sc. 

 Government Botanist and Mycologist, Ceylon. 



IT is now thirty-two years since the first Hevea tree was 

 tapped in the Eastern tropics. The Brazilian methods, 

 described by Cross, were adopted, and for the next fifteen 

 years those methods what would now be termed "in- 

 cision " methods held the field. A great advance was 

 made when Ridley described the now typical Eastern 

 method of reopening the cut, a method which more than 

 anything else made plantation rubber a commercial possi- 

 bility. But in the early days of this " excision " method 

 the cuts were not reopened for more than about fourteen 

 tappings; that is, only until about I in. of bark had been 

 removed. The method now in vogue of gradually remov- 

 ing the whole of the cortex to a height of 3 or 6 ft. 

 dates from about 1904. This sequence is worthy of 

 remembrance, since it explains many of the recommenda- 

 tions of the pioneer advocates of rubber planting which 

 to-day appear so obviously wrong; they never contem- 

 plated such treatment as the tree now undergoes. 



Early tappings, even in botanic gardens and experiment 

 stations, were merely " tappings for yield," i.e., it was 

 simply desired to ascertain whether the trees would yield 

 rubber, and, if so, how much. It is rather to be feared 

 that this phase, necessary twenty years ago, has persisted 

 to the present day, though scarcely any country can now 

 remain in which such tapping can be justified as work 

 for an experiment station. According to current ideas, 

 tapping experiments should be carried out as far as pos- 

 sible on virgin trees, and it is a waste of material to 

 sacrifice such trees without endeavouring to obtain further 

 evidence on some definite problem. And the experi- 

 menter should not permit himself to be deterred by the 



