September, 1911.] 



195 



Saps and Exudations. 



paring is to be followed by pricking, the 

 former is not as deep as it otherwise 

 would be, and therefore does not inter- 

 fere with the circulation as seriously as 

 it might otherwise. The paring alone 

 was expected to get all the latex. These 

 close cuts have been made for several 

 months, but not yet long enough to 

 determine whether they might be 

 injurious. Of course, the chance of 

 injury can be lessened by the avoidance 

 of too frequent tappings. 



Tapping Intervals. 



" The yield from a given tree appears 

 to increase for the first six to twelve 

 tappings, after which it decreases some- 

 what till a point is reached where it 

 remains about constant. The word 

 ' tapping ' includes the pricking too. 

 Hence a series of six, nine or twelve 

 tappings may well be followed by a rest. 

 For instance, if the yield diminishes 

 after six tappings, it might be well to 

 rest it. Probably twelve tappings 

 should be made. We have found that 

 a rest of a week is sufficient at some 

 periods. In this way we remove all the 

 bark we can. If we start from the tree, 

 our next two parings will remove that 

 portion, and then the next time we take 

 off some more bark, when pricking 

 comes immediately after the removal of 

 the bark. This pricking takes place as 

 soon as the bark is removed. 



" If a third of an inch is removed at 

 each paring, then in three parings, or 

 nine tappings, one inch of bark will 

 have been removed, and there is plenty 

 of authority for advocating a rest at 

 this stage. We have found that a rest 

 of a week or ten days is sufficient, and 

 then we start again and get about the 

 same result. At this rate, also, fifty- 

 four tappings will take off all the bark 

 between adjacent cuts. Therefore, 

 tapping for one week and resting for 

 three weeks would remove all the bark 

 on one side of the tree in about six 

 months, when it must be rested before 

 beginning on the other side. 



" The more rubber we get from each 

 tree at each tapping, the more economi- 

 cal the tapping. After the bark on one 

 side of the tree has been removed for 

 tapping, after six months ' rest we 

 would go around to the other side of the 

 tree. It has been found by the experi- 

 ment station reports and observations 

 that, if the tapping is carefully done and 

 not too deeply, it will renew in less 

 than a year. It is only in certain points 

 and when the pricking is too deep, that 

 swellings on the wood are caused. If 

 the pricking is carefully done, it does 

 not swell, but the pricking does go into 



the most prolific cells, while in order to 

 get there with the knife we would have 

 to cut deep, because the bark is so thin. 

 Thus far we have not found satisfactory 

 knives. 



Alternate Tappings. 



il A movement is on foot, and growing, 

 in the Par East, to limit tapping oper- 

 ations in any one year to a quarter or a 

 third of the tree, instead of to a half, as 

 heretofore, thus giving three years 

 instead of two for the tapping surface to 

 be renewed. This might well be con- 

 sidered by us, in which case, instead of 

 the full herring-bone going half around 

 the tree, the half herring-bone going one 

 third around, might be used. Of 

 course this system of tapping is not the 

 last word in the tapping of Oeara trees, 

 but in practice it has shown advantages 

 over any of the other methods tried, and 

 is the best we have found so far ; 

 furthermore, the best returns, in the 

 use of this method, were obtained in the 

 series of experiments carried out by the 

 Board of Agriculture and Forestry and 

 the Experiment Station last year, and 

 these were obtained by making two 

 vertical cuts, two in each place and at 

 each tapping. They were made with 

 knives, and a number of the cuts were 

 too deep; a number of the trees have 

 been thus injured. The chief objection 

 to it in my mind is that it does not 

 admit of a sufficient number of tappings 

 in each year. If we can discover some 

 other method of getting at the same 

 result, I think we will find it better, 

 provided we can secure sufficient labour- 



" When the vertical cut is made, there 

 is a tendency in the bark to crack open- 

 that is, the wood part of the bark cracks 

 open, and this is apt to cause an injury 

 that is difficult to heal, and it makes the 

 bark rust. Aside from that, I have not 

 seen any reason to believe that one will 

 heal before the other. I have not seen 

 any difference in that respect. We did 

 try making vertical cuts on the tree, 

 and found it more difficult to do the 

 tapping in that way without injuring 

 the tree. 



Other tried Methods, 

 " Other methods that have been tried 

 with Ceara trees are : vertical cuts- 

 paring, spiral cuts, V's, pricking and 

 collecting, pricking and acetic acid, 

 paring and pricking simultaneously. 



"The latex cells lie so near the 

 cambium in these trees that it is difficult 

 to cut with a knife deep enough to get 

 all the latex without injuring the 

 cambium. A knife with the right sort of 

 guard will in a measure overcome this 

 difficulty, but no satisfactory knife of 



