120 THE PARA RUBBER TREE 



in circumference, but it has hitherto been held to be 

 disadvantageous to tap the trees until they have attained 

 this size. Analyses made by Bamber in Cejdon (see 

 p. 5.3) have shown that the rubber from two-year-old 

 Para trees does not differ very markedly in composition 

 from that derived from older trees, but it is generally 

 agreed that the rubber from young trees is very deficient 

 in physical properties, being soft and weak. In view of 

 this fact and of the small yield of rubber obtainable from 

 young trees, it is not usually desirable to tap Para trees 

 before they are at least four years old. 



The thickness of the cortex of Para trees of suitable 

 size for tapping varies from ^ to ^ in. according to the 

 age of the trees. It has been pointed out already that 

 the greater number of the laticiferous vessels are situated 

 in the innermost layers of the cortex, so that in order 

 to obtain the maximum flow of latex it is necessary to 

 cut sufficiently deeply to reach these layers. Great 

 care should, however, be taken not to penetrate the 

 Avood nor to injiu-e the cambium, as if this is done, the 

 healing of the wound is retarded and the renewed bark, 

 instead of being smooth, is likely to develop excrescences 

 which seriously interfere with subsequent tappings. 



Tapping is usually restricted to the basal portion of 

 the trunk up to a height of about 6 ft., as it has been 

 conclusively proved that the greatest yield of latex and 

 rubber is obtained from this area. Experiments on 

 tapping the higher portions of the stem show that not 

 only is a smaller yield of latex obtained, but that the 

 rubber is usually more resinous. In view of these results 

 and of the additional labour involved, it is not usual to 

 tap above a height of 6 ft. 



Tapping is best performed in the early morning or 

 late in the evening, as it has been found that during the 

 day, when transpiration is active, the flow of latex is 

 retarded. Experiments made by Ridley at the Botanic 

 Gardens in Singapore showed tha! morning tappings 

 furnished a larger yield of rubber than those made in the 

 evening. 



Large luunbers of special tapping tools have been 

 introduced for use on plantations, and almost every 

 plantci' has liis own views as to the best type of instrument 

 to use. Many of the knives are of very complicated 



