177 



protected with the root and foliar systems, and consequently 

 expenses in weeding are greatly checked, and soil loss thereby 

 reduced ; (3) the rubber can be harvested cheaper; (4) the cultiva- 

 tion is essentially one of rubber trees which presumably have a 

 higher value than other trees of economic importance, and the 

 method of cultivation over all the soil becomes the same ; (5) the 

 inevitable proportion of poorly developed, stunted, and damaged 

 trees is not as serious ; (6) it is easier to thin out a densely planted 

 estate than to interplant a widely planted one. 



The disadvantages are(i)there may be considerable interference 

 in the development of all parts of the plant and the resultant 

 trees be dwarfed and lacking in vitality ; (2) the stems will tend 

 to become thin, long, and spindly, and the thickness of tappable 

 cortex (bark) reduced ; (3) diseases are given a greater certainty 

 of originating and may spread more rapidly because the parts of 

 the plant are nearer to one another or in more frequent contact. 

 DISTANCE ACCORDING TO SIZE AND AGE. 



The cultivation of trees of Hevea brasiliensis ranks as unique in 

 so far as it has to deal with a species which grows into a tree of 

 enormous size; the past and most of the present products, in 

 Ceylon, cannot be compared with the latest arrival, for it overtops 

 the tallest cacao and cinchona trees, and often equals the coco-nut 

 palms, in height and frequently in breadth, age for age. 



Trees less than thirty years old, which have never really been 

 cultivated, have a height of 80 to 90 feet and a circumference of 

 80 to 109 inches ; specimens planted 25 to 30 feet apart have been 

 known to overlap their branches in about 20 years, and fifty years 

 old trees in tropical America even exceed these huge dimensions. 

 This is the outstanding difference between the cultivation of Para 

 rubber trees and all other plants in Ceylon, and though it has 

 been an easy matter in the past, to settle the distance at which 

 tea, cacao, cinchona, &c, should be planted, we are now confronted 

 with a new set of conditions which may require different methods 

 of cultivation. 



DISTANCE OF TAPPED TREES. 



There is another point which appears to have been overlooked 

 in connection with this subject, and that is the retardation, in 

 growth, which must follow regular paring or tapping. It is no 

 exaggeration to say that most of the old trees in Ceylon were not 

 systematically tapped until the last few years, and but few estates 

 can point to acreages which have been regularly tapped throughout 

 successive years, from the time the old trees attained their minimum 

 tappable size. Whenever cortical tissues are removed or mutilated, 

 the energy of the plant is partly diverted to the production of new 

 tissues in the affected area, for the time being the intimate 

 connection between individual vital structures and that of the 

 latter with cells which have less important functions, is interrupted ; 

 such changes must affect the future development of the plants, 

 especially when of repeated occurrence from the 4th, 5th or 6th 

 years onwards. In the absence of any measurable effects following 

 the tapping of trees, one can only generalise and state that the 



