PARA-RUBBER CULTIVATION 607 



trees. Then it is an undoubted fact that rubber from quite 

 young trees or twigs of Hevea is very deficient in elasticity. 

 There has consequently been much opinion expressed to the 

 effect that the latex takes some time to mature and so naturally 

 it is argued that the rubber from old trees must be better 

 than from young ones. But the botanical fact is lost sight 

 of that new laticiferous elements are continually being added by 

 the cambium to the bast, no matter what age the tree may be. 

 These must take time to mature. Previous to their full develop- 

 ment they are not likely to yield an appreciable quantity of 

 latex. Hence, unless the latex alters its character as the tree 

 grows older, there is no reason for thinking it is less mature 

 in a six or ten-year-old tree than in a fifteen or twenty-year-old 

 one ; both will have immature laticiferous tubes as well as fully 

 functional ones. 



The reason why the latex from young stems and shoots 

 yields an inferior rubber may be associated with the fact that 

 this latex is contained chiefly in the tubes formed in primary 

 growth. These may quite well differ in their contents from 

 those produced in the so-called secondary growth, which is due 

 to the activity of the cambium and by which the tree increases 

 its girth. If there be any truth in this supposition, then this 

 will account for the fact that the rubber from Hevea trees 

 under four years old, and especially of Castilloas of a similar 

 age, is midway in strength between that from the shoots and 

 that from older trees. In such young trees the primary 

 laticiferous tubes will still be yielding some latex, which will 

 mingle with that from the secondary tubes, giving an inter- 

 mediate product. Later the primary ones will become wholly 

 compressed by the growth in thickness, and cease to give any 

 latex. 



Further, direct testing of the rubber seems now to be 

 dispelling this notion of an inferiority in the caoutchouc from 

 six to ten-year-old trees, as compared with that from older 

 ones. Beadle and Stevens ! have carried out interesting 

 vulcanisation tests with plantation rubber and fine Para. They 

 argue rightly that, as almost all rubber is vulcanised before 

 use, the trials of comparison should be made after, and not 

 before, vulcanisation. Their results are distinctly favourable 

 to plantation rubber. Tests for tensile strength and elongation 

 1 Beadle and Stevens, Chem. News, 1907, 96, 37, 187. 



