62 THE TAPPING OF RUBBER PLANTS 



over one-fourth of the circumference. After tapping 

 for five months, by means of the Bowman-Northway 

 parer or the parer and pricker alternately, the distribu- 

 tion of starch in the stem was determined. It was found 

 that no starch or reducing sugar was present in the zone 

 of bark within 2 in. of the top or sides of the uppermost 

 incision, but that above this area the bark and wood 

 contained abundant starch ; that no starch or reducing 

 sugar occurred in the strips of bark between the in- 

 cisions, although starch was present in the wood below ; 

 that starch could not be detected in the bark within a 

 distance of 6 in. below the lowest cut ; and that no 

 starch or sugar was present in the renewed bark on the 

 incisions nor in the outer layers of the wood below. In 

 all other parts of the stem there was an abimdant supply 

 of starch. This method of tapping has therefore only a 

 local influence on the distribution of food-materials in 

 the stem, and is not likely to affect adversely the vitality 

 of the tree. 



From the results of his experiments Fittmg concluded 

 that, in the case of young trees especially, the fuU spiral 

 method of tapping cannot be recommended, nor indeed 

 any other system in which the incisions cover practically 

 the whole of the circumference of the stem without leaving 

 continuous vertical strips of untapped bark, sufficiently 

 wide to maintain the necessary connection between the 

 crown and the base of the tree. He suggested that 

 the safest and most rational plan would be to divide the 

 tappable surface of the stem into four vertical sections, 

 and to tap each of these in rotation by the half- or full- 

 herringbone system, each section servmg for a year's 

 tapping. In the second year the quarter opposite to the 

 first would be tapped, and then the others in rotation. 

 In this way four years would elapse before it was necessary 

 to tap the renewed bark on the first quarter, and sufficient 

 connecting strips of untapped original or renewed bark 

 would always be maintained to carry on the vital functions 

 of the plant. In the case of large trees the stem can be 

 divided into eight vertical sections and the two opposite 

 sections tapped simultaneously in rotation. 



Fitting also drew attention to the advisability of 

 allowing the trees to rest between successive tapping 

 periods in order that the reserve food-supply, which wiU 



