- 35 ' 



before a fresh supply of organic material can be conveyed across 

 the tapping spot, because a sufficient number of channels will 

 have to be reproduced by the cambium for this purpose. 

 Judging from observation, Hevea requires quite a long time for 

 this to be effected. Without special experiments, it is impossible 

 to determine, how long a period must elapse before the food 

 deficiency at the base of the tree can be made good by a fresh 1 

 supply. 



This extremely important question arose only after I had 

 ascertained the effect of incisions on the transport of nutrient 

 sap, and it was therefore only at the end of my stay in the tropics, 

 that I might have been able to investigate this subject had I had 

 some trees at my disposal which had been tapped for some time 

 previously. I feel sure that, on the lines I have indicated, I could 

 easily and rapidly have solved this question. It is certainly 

 important to strive to solve it as soon as possible. 



Finally, it is important, not only to ascertain how soon the 

 transport of a certain amount of food material across the tapping 

 surface can again be proved to exist, but also, and chiefly, how soon 

 after the end of one tapping period it is possible to transport a 

 large enough quantity of material towards the base of the tree to 

 satisfy the probable very great need of food, which has arisen 

 in the bark during and after the tapping period, in consequence of 

 the necessary renewal of bark and latex, and also, how soon the 

 reservoirs of the tree can be refilled. I feel sure, that a long 

 time must elapse before the latter will be possible, and probably 

 this may not be till the reproductive activity has all but ceased its 

 work. This question, too, could be solved very rapidly by an 

 investigation of trees which had been tapped some length of time 

 previously. It is evident how necessary the refilling of the 

 reservoirs is, for the maintenance of the tree's life after a repetition 

 of the tapping operation. If the reservoirs have not been refilled 

 completely, the tree will enter the second tapping period with 

 a much smaller quantity of reserve material than at the first one. 

 The result will necessarily be, that, at a second, third, or subsequent 

 tapping, the reserve material will have been completely exhausted, 

 that tin tree will be injured severely, and that tin- latex will 

 deteriorate considerably. I do not think it at all unlikely, on 

 the contrary it is very probable, that in thi^ manner, in. my bad 

 results can be accounted for, that pi, inters have had, with regard 



