Treub. for the kind way in which he met my requests. In the 

 same way I owe grateful thanks to the Directors of the Large and 

 Small Botanic Gardens, Mr. Pit and Dr. Tromp de Haas. 

 Both these gentlemen were constantly ready to assist me. Mr. Pit 

 had also the great kindness to let several older Hevea trees be 

 tapped according to my directions for some months, and to 

 sacrifice them afterwards for an examination. Dr. Tromp de Haas 

 with equal kindness, caused the incisions in some plants to be 

 covered with soil and coconut fibre. It is conceivable that the 

 number of old Hevea trees that could be placed at my disposal 

 in Buitenzorg was not sufficiently large to enable me to solve the 

 tapping problem completely. Too much must, therefore, not be 

 expected from my experiments. They can do no more than point 

 out a way, which by experiments on a larger number of trees, 

 might lead us in a comparatively short time to a comclusion as to 

 which of the tapping systems must be condemned as harmful. 



But anyhow, my experiments will supply many valuable data, 

 on which it will be possible to base decisions with regard to the 

 various tapping methods, at least as far as Hevea is concerned. 

 How far the conclusions at which we have arrived in the case of 

 Hevea are also applicable to other rubber plants, future 

 experiments alone can decide. 



