20 



Willis and Parkin, that the latex will only begin to flow freely 

 from incisions that are made one or a few days after the first 

 incisions. 



The following process seems to be the basis for all tapping- 

 methods at present in use. A number of shorter or longer oblique 

 incisions are made in the stem of the tree, each a fair distance 

 above the other, and at intervals of one or more days, small strips 

 of bark are pared off with the tapping knife from the lower edge 

 of all the tapping incisions and along their whole length. This 

 process is repeated, till eventually the whole of the cortex and 

 almost all the bast has been pared off down to each next lower 

 incision. It is regarded as a matter of great importance, that 

 each time a very narrow strip of bark only should be removed, 

 so that it should take as long as possible to complete the entire 

 removal of the cortex, and for the tapping period to come to an 

 end. In order to prolong the time, and to spare and preserve as 

 much bark as possible, a favourable view has been taken of a 

 suggestion, which has been adopted in practice on many estates, 

 to make the incisions with the knife less deep, and at repeated 

 tappings, not to use the knife each time, but alternately the knife 

 and another instrument invented for the purpose, the pricker. 

 This pricker is a small star-shaped wheel with sharp teeth. It is 

 applied on the inner edge of the last incision made by the knife. 

 By moving it with an appreciable pressure along the whole length 

 of the tapping surface, those laticiferous vessels are severed that 

 are situated in the inner parts of the bast, and which have become 

 exposed by the last incision; and by this process the greatest 

 possible drainage of all vessels is obtained. The pricker should 

 penetrate as far as the cambium, but must not cause any injury 

 to this creative tissue. It seems that there is still a great diversity 

 of opinion as regards the advantages of the use of the pricker. 

 I shall refer to it again. 



Two facts are thus characteristic of almost all tapping methods 

 in vogue : firstly, the entire severance by oblique cuts of extensive 

 areas of cortex and bast. The result of this severance is an 

 interruption in the stem of numerous channels for organic 

 substances. Secondly, the gradual removal of very large surfaces 



question here of root-pressure, but of fluid secretions of living cells 

 in the neighbourhood of the wound. Compare L. Jost, Pflanzen- 

 physiologie. G. Fischer, Jena, 2nd ed. Pages 64, ff. 



