60 PARA RUBBER. 



Single Oblique Cuts. 



It should be explained at this point that the laticiferous tubes 

 from which latex is obtainable in large quantities are mainly dis- 

 posed internally — very near the cambium — and for the most part 

 run through the cortex in a vertical direction. 



It should also be remembered that the latex, even when most 

 dilute, is apt to rapidly coagulate on the tree and to form scrap 

 rubber. A cut made horizontally will not conduct the latex to a 

 central point, and horizontal tapping is invariably accompanied 

 by a large proportion of scrap owing to the latex trickling down 

 the stem and drying there. A vertical channel is naturally the 

 best for conducting the latex to a desired point, but it is as extra- 

 vagant as it is unnecessary in most cases. Parkin proved that 

 simple incisions made in an oblique direction gave about double 

 the yield of latex as either the vertical or horizontal, the latter two 

 showing very little difference in yield of rubber. Each oblique 

 cut may be from one to six or more inches in length, but a distance 

 of nearly one foot apart should be allowed. The oblique incision 

 is practically the basis of most other methods now in use, and is 

 spoken of as the half-spiral system when the incisions are of con- 

 siderable length. 



In this system collecting cups can be placed at the base of each 

 incision, but an invention for conducting the latex from all the in- 

 cisions to a central basal coil has been brought forward, which, if 

 adopted, will add greatly to the value of this system of tapping. 



V Incisions. 



The V incision is nothing more or less than a duplicated or double 

 oblique system. The sides of each V may be from 2 to 12 inches in 

 length with the apex of the V at the lowest point, The yield obtain- 

 able from such incisions is generally, but not always, about double 

 that obtained from a single oblique cut, and having one centre for 

 two incisions seems to be one of the greatest advantages of this sys- 

 tem. The V's are usually made on the stem from the base up to a 

 height of six feet, and are distanced about six inches apart. The 

 open end of the V is usually about six inches wide. There is, however, 

 a great variation in the size of the cuts, the smallest incisions 

 measuring about one inch in length. 



It has been suggested that the reason why the quantity of latex 

 obtainable is not double that from a single oblique line is because 

 the lines are very close to one another and may draw on the same 

 system of laticiferous tubes, a conclusion which is warranted by the 

 results of many experiments in various parts of Ceylon. In addition 

 to this drawback there is also another serious result which often 

 accompanies this method of tapping, viz., the loosening of the bark 

 on drying and tapping from the apex of the V upwards. 



