110 PLANTING IN UGANDA 



CHAPTER XII. 



Collection and Preparation of Rubber 



Implements. The selection of these is the first 

 consideration in commencing to tap ; and the many 

 patent tapping knives existing offer a wide range 

 of choice. Many knives are made with attached 

 guards, which render it impossible to tap beyond 

 the depth for which the knife is set. Theoreti- 

 cally, this is exactly the principle required in a 

 knife to be used by the native labourer, but, unfor- 

 tunately, the bark differs enormously in thickness 

 on individual trees, and as the only section con- 

 taining the lactiferous vessels is the inner layer of 

 bark, tapping at a uniform depth throughout the 

 plantation would produce little Eubber. The sort 

 of knife we have described would have to be set 

 differently for almost every individual tree, and a 

 mistake in setting would have as ill results as deep 

 tapping without it. It would, in fact, call for as 

 much discrimination on the part of the tapper as 

 the use of an unguarded knife. 



