Sept. 1906.] 



221 



Saps and Exudations. 



THE MOST DRASTIC SYSTEM OF TAPPING. 



Mr. Thornhill :— There are one or two points in your previous lecture I 

 should like to have explained. Mr. Thornhill then read the following extract from 

 Mr. Wright's lecture :— 



" You get more rubber in a given period of time from the full-spiral than 

 from the herring-bone or by the half-spiral cut. When you come to workout the 

 weight of rubber obtained per unit of bark excised, you find the full-spiral gives 

 you the maximum rubber per square inch of bark cut away, and it may be con- 

 sidered the best system for places requiring thinning out." 



Mr. Wright :— Several people have brought this subject forward, and many 

 seemed to wonder whether my statement meant that the full-spiral system, since 

 it gives the maximum yield in a given period, was to be recommended on those 

 grounds alone, or whether it was only to be recommended for estates which have 

 to be thinned out. Iu my opinion there can be no questioning the statement for a 

 single moment that the full-spiral system is the most drastic one that can ever be 

 adopted in tapping. At the same time, if it is carried out properly, it is not the 

 species of ringing which many people seem to think it is. At Henaratgoda we have 

 been tapping for nearly a whole year, but, as you can see from these photographs, 

 we have only worked through two or three inches of bark, though the tapping- 

 lines are above twelve inches apart, so that, even with the spiral system, we can 

 go on tapping the original bark for three years. We can commence to tap the 

 renewed bark when it is three to four years old. We know that the average Para 

 rubber tree does not produce mature bark, fit for tapping, under four years. 

 Renewed bark is a new creation, and the process of decomposition leading to the 

 formation of latex tubes goes on in the same way as in the original bark ; for the 

 completion of these changes much time is required. The full-spiral system strips 

 the whole of the bark ; it gives a larger yield than some other methods, though 

 it is probably less economical. As I pointed out, any method which is of such an 

 extensive character as the full herring-bone, or full-spiral gives you a low yield 

 per unit of bark excised. The photographs illustrate this point. 



THE USE OF THE PRICKER. 



Mr. Thornhill : — Might I ask whether in these photographs the Northway- 

 Bowman tapping knife was used ? Did it cut through the cambium? 



Mr. Wright :— You can see where the pricker has been used ; the impressions 

 are visible on the photograph. Without a shadow of a doubt, the pricker reaches 

 the cambium ; the use of the pricker is to be recommended, but at the same time 

 it should be remembered that it is disadvantageous in so far that it touches the 

 cambium. I have examined such areas, but have not seen any very bad effects. 

 Of course, the greater number of the latex tubes are disposed internally ; they 

 are found in largest proportion near the cambium, and you require the pricks to 

 get at them. You can, with advantage, leave a good thickness of bark over this 

 inner layer, and reach the latex tubes by means of a pricker. 



TAPPING THE CAMBIUM. 



Mr. Thornhill :— Many of us have experienced that if you don't tap into 

 the cambium you don't get good results. 



Mr. Wright :— Quite so, but it is not necessary to cut down right into the 

 cambium to get the latex. The laticiferous system is outside the cambium or 

 the wood. 



Mr. Thornhill remarked that very often rubber was found coagulated 

 inside the bark, and when they pulled the bark off, they found pieces of rubber 

 in the woody portion of the tree. 



