PREFACE. 



\Yhen I went to Java in the Autumn of 1907, having obtained 

 the German so-called Buitenzorg grant, it was, amongst other 

 things, mv intention, bv studying: rubber plants in the tropics, to 



ERRATA. 



Page n, line 5 read organic instead of inorganic. 

 Page 14, footnote read Fo/. 94 instead of Fo/. /. gj. 

 Page 22, footnote read Icintlosc instead of cevnlose. 

 Page 45, line 20 read bark instead of latc.v. 



Page 48, line 16 read distribution of substances instead of sap 

 distribution. 



are imperative in order, by introducing rational tapping methods, 

 to protect rubber plantations against very unpleasant earlier or 

 later injuries. It is extraordinary, that the opinions on the advan- 

 tages of the various tapping methods so far recommended, are 

 not based on experiments, such as our general physio- 

 botanical knowledge suggests, and which have a definite 

 object in view. It is likewise strange, that there is an utter lack of 

 effort, by minute scientific research, to clear up the points 

 on which the experiences of planters are at variance. 

 Consequently a great uncertainty of opinion still prevails, which 

 can only prejudice the cultivation of rubber. I\. < o^m/nl 

 authorities in the field of rubber investigation have not bri-n able 

 to shut their eyes to this fact. From the literature on the subject 



