it would almost appear, as if in this connection it was not yet 

 sufficiently recognized, how important it is that theoretical and 

 practical research should go hand in hand. If from the very first 

 an endeavour had been made to keep in close touch with scientific 

 botany, I feel sure that many mistakes in the cultivation of rubber 

 would have been avoided, mistakes, the consequences of which 

 may for many years injuriously affect many plantations. Rubber,, 

 more than any other cultivation, stands in need of being constantly 

 supported by science, because in rubber planting many very 

 complicated scientific problems of various sorts have to be 

 considered, which cannot in any way be solved without due regard 

 to theoretical botany, and in practise very important demands are 

 made, the fulfilment of which must greatly depend on the solution 

 of these problems. For the more the world's production of 

 rubber increases, and the price drops, the more necessary it is 

 for producers, by rational methods, to get the most out of their 

 plantations. 



As a whole series of questions for investigation actually force 

 themselves on any physiological botanist, who wishes to decide 

 on the suitability of the various tapping methods that have been 

 recommended, it seemed to me a profitable task, to determine, 

 whether research carried out from scientific points of view might 

 not promote our knowledge of the practicability of the tapping 

 systems considerably, and should this supposition prove correct, 

 to show the way we should follow in investigating the tapping 

 methods with regard to their utility. 



Before beginning my investigations, I inspected a number of 

 old rubber plantations, noted for their excellence and productive- 

 ness, and in conversation with planters, obtained a certain amount 

 of insight into their methods, experiences and results. A stay in 

 Ceylon offered the best opportunity for this. 



Hevea offered itself, so to speak, of its own accord as a fitting 

 object for my experiments. Firstly, it still occupies the first 

 place amongst rubber plants. With regard to no other tree, 

 therefore, is it of such pressing importance to increase our 

 knowledge of the utility of the various tapping systems. Secondly, 

 Hevea was the only rubber plant, of which at Buitenzorg in Java, 

 I was able to obtain some specimens for my experiments. I should 

 not like to miss this opportunity of expressing my warmest thanks 

 to the highly esteemed Director of Agriculture, Professor Dr. 



