2 1 



of cortex and bast, together with the extraction of large quantities 

 of latex. This necessitates an extremely extensive renewal of bast 

 and latex in the stem, for which purpose a large extra expenditure 

 of organic substances is required. These substances will have 

 to be obtained all the more exclusively from the reservoirs in the 

 stem, the more the downward current of food supplies from the 

 crown has been checked by tapping the tree. The expenditure of 

 material, as compared with a tree in its normal condition, is all 

 the more increased, in that the intensity of respiration is far 

 greater at any wounded parts of a plant, than at the uninjured 

 ones. 



I think all these facts and considerations demonstrate with 

 sufficient clearness the necessity for investigating the influence 

 which the various tapping methods exercise on the distribution 

 of sap in the stem, and for ascertaining how far tapping 

 injures the tree by checking the downward current of sap. 

 It is only by such investigations that we can in time solve the 

 extremely important question, how much nutritive substance must 

 be present in the stem below and within the wound in order to 

 provide not only for the renewal of the removed bast, but also for 

 respiration, for the continuation of the normal growth in girth, for 

 the continued development of the root-system, as well as for the 

 reproduction of latex in its original quantity and quality. It is 

 conceivable and even probable, that a deterioration of the renewed 

 latex begins to show itself even before all the reserve material in 

 the reservoirs has been exhausted, in fact as soon as the growing 

 tissues completely absorb and utilise the reserve. 



The objection might be raised, whether there is still any need 

 for such investigations, whether the experience gained in practice 

 will not yield sufficient information as to which of the tapping 

 methods injure the tree and will in time cause a deterioration of 

 the latex. The answer to this must be; firstly, that the views of 

 planters on the value of the various tapping methods differ very 

 much and contradict one another; secondly, that the injun. - 

 resulting from bad tapping systems need not necessarily be very 

 apparent till after the lapse of several years. I shall discuss this 

 more in detail further on. It is against a fate of this sort that \\ 

 must as much as possihl guard rubber plantations by invrMi^.i- 

 systematically conducted. For of \\hat use' are estates, \\liich 

 s during a period of four to six years yi.-ld plentifully, but 



