i Gums, Resins, 



300 



f April 1908. 



each nine years old and of practically the 

 same circumference, one of which yielded 

 tour pounds of rubber during the same 

 period as the other (tapped the same 

 number of times) gave little more than a 

 quarter of a pound. 



Various objections have been urged 

 against the selection of Hevea. These 

 are successively answered by Mr. Vernet. 



1. It has not been actually proved 

 that selection will have any effect upon 

 Hevea. 



But there is no case recorded among 

 either animals or plants in which selec- 

 tion when tried has not been effective. 



2. The trees cannot be tested until 

 eight years old, so that each step in the 

 process will take eight years at least. 



But each step will almost certainly 

 mean a marked improvement. 



3. Many people are satisfied with the 

 yields already obtahied from Hevea. But 

 compare the case of Cinchona where 

 the practice of selection in Java has 

 killed out the industry in Ceylon. 



4. Seed is so scarce that it is necessary 

 to sow all that can be obtaiued. This 

 objection is now, at any rate, out of 

 date. 



5. It is thought that cross-fertilization 

 between different trees will nullify the 

 effects of selection. This can be got over 

 by the removal of inferior trees. 



6. The great amount of labour en- 

 tailed. 



The present paper shows that a com- 

 paratively few tests of each tree will be 

 sufficient, 



7. The individual differences may 

 diminish with the age of the trees. 



Mr. Vernet's experience shows that 

 this is not the case. 



Various practical notes and suggestions 

 are given with regard to methods of 

 selection, after the separate tapping of 

 individual trees has been carried out ; the 

 following classification is suggested :— 



1. Trees giving a high yield ; the seeds 

 of these should be planted by themselves 

 in order to afford the material for future 

 selection. 



2. Other trees giving a yield above 

 the average ; the seed of these should 

 be selected for general planting. 



8. Trees below the average. Their 

 seeds should not be used. 



4. The very worst trees should be cut 

 down and replaced by selected seed. 



Mr. Vernet concludes by remarking 

 that only those who run their plantations 

 on scientific lines can hope to retain a 

 high scale of profits iu the future* 



RUBBER. 



Some of the older plantations of Chia- 

 pas and Tabasco, Mexico, are quite 

 extensive and have been producing 

 rubber for a number of years. Visits to 

 such plantations have afforded addi- 

 tional evidence of the practicability of 

 securing considerable quantities of rub- 

 ber from planted trees, but they also 

 supply an additional reason for caution 

 in enterprises based on the Central 

 American rubber tree, for it is being 

 found that the bark in the proximity of 

 old cuts yields very little latex, so that 

 the profits still remain uncertain. The 

 rubber-forming materials of the latex 

 are restored only slowly, if at all. The 

 first cuts yield much more latex than in 

 the Para rubber tree, but there is no such 

 persistent production of latex nor any 

 repeated flow to be obtained by paring 

 back the edges of wounds which produce 

 in the Para rubber tree more latex than 

 the previously uninjured bark. 



The effects of destroying the forest 

 conditions and of exposing the soil to 

 the sun and to the washing of the rains 

 is shown in the backward condition of 

 plantations on the Isthmus of Tehuan- 

 tepec. Unless the soil is unusually fer- 

 tile and well watered, the trees maintain 

 a more rapid growth when they have 

 the advantage of a surface mulch 

 afforded by a partial or gradual clearing 

 away of the forest. 



The latex of Castilloa is also quite 

 different from that of the Para rubber 

 tree, and requires different methods of 

 treatment. With slow coagulation the 

 quality of the product deteriorates. 

 Exposure of the latex to air and sunlight 

 by spreading it out in thin layers pro- 

 duces better and more durable rubber 

 than bulk coagulation, even with the 

 thorough and repeated washings which 

 are now generally advised. — U. S. Depart- 

 ment of Agriculture, Report for 1907 of 

 Bureau of j'lant Industry. 



THE PROPER DISTANCE FOR 

 PLANTING HEVEA. 



By M. O. Labroy. 



The subject is here discussed at some 

 length from various points of view, and 

 the opinions of planters in Ceylon and 

 the Federated Malay States are quoted, 

 as well as those of Messrs. Wright and 

 Carruthers. It is pointed out that Cacao 

 is the only crop suitable for growing per- 

 manently in the same land as rubber ; 

 tea, coffee and camphor can only tem- 

 porarily occupy the intervening ground. 



In its natural habitat, trees of Hevea 

 are seldom found closer together than 

 8U feet* and the reason seems to be that 



