82 RUBBER AND 



The yield of latex at six feet from the ground was 

 rather more than three-fifths of the yield at two feet in 

 the case of this particular experiment. The only reason 

 for confining tapping to the lowest six feet of the trunk 

 is therefore one of convenience. Profitable yields could 

 doubtless be obtained at a considerably greater altitude, 

 but this would entail great loss of time in tapping, owing 

 to the necessity of climbing the tree. 



Effect of tapping on the composition of the latex. 



The increase in flow associated with wound response 

 is accompanied by a reduction in the concentration of 

 the latex. Hence in terms of latex the increases in 

 yield during the early stages of tapping would be larger 

 than those shown in the various tables in the present 

 chapter, which refer to yields of dry rubber. Table XXI 

 illustrates this fact. This table is the counterpart of 

 Table XI, except that the entries refer to percentages of 

 rubber in the latex, instead of to weights of dry rubber. 

 Table XXI further shows that the falling off in concentra- 

 tion is much more rapid when the tapping intervals are 

 small than when they are larger. After a certain period, 

 which is longer when the intervals are longer, a more or 

 less permanent concentration is reached, which persists 

 for an indefinite period, but is also subject, as in the case 

 of the yield of dry rubber, to seasonal variation. This 

 more or less permanent concentration is considerably 

 higher in the case of the trees tapped at longer intervals. 



