56 CENTRAL AMERICAN RUBBER TREE. 



the undergrowth will also discourage the rubber, and the decrease of 

 such shade will increase the competition of the undergrowth with the 

 rubber. The ideal of rubber culture does not require a roof of shade 

 over the rubber trees nor a dense growth of bushes and vines under 

 them. The roof should be of Castilla foliage, and the ground should be 

 covered by a mulch of dead leaves and branches, which enrich the soil 

 and assist in the retention of moisture. 



CLEAN CULTURE WITH FOREST PROTECTION. 



If, then, the requirements met by close planting be eliminated from 

 the shade question there remains little beyond the fact that in districts 

 in which the dry season is unduly long it may be unwise to shorten 

 the period of growth by cultural methods which increase the daily 

 exposure to too dry an atmosphere, as there can be no doubt that the 

 clearing of large tracts of land will mean warmer aud relatively drier 

 air, and that the dryness of the air near the ground will be further 

 increased by the wind, against which the forest will no longer afford 

 protection. It might accordingly be good policy on large estates not 

 to clear continuous tracts for planting, but to leave belts of forest to 

 break the wind and keep the atmosphere moist. This method would 

 be particularly convenient where the land is to be cleared by burning, 

 since in a tropical forest the trees often grow with their branches inter- 

 laced or are bound together by large climbing vines or lianas, so that 

 it is often much easier to clear an entire strip of forest than to leave 

 individual trees standing at anything like regular intervals. 



METHODS OF HANDLING CASTILLA SEEDS. 



The thin-skinned seeds of Castilla, like those of so many other trop- 

 ical plants, are adapted only for germinating on the moist soil of the 

 forest. Instead of having a hardened shell for protection, there has 

 developed only a fleshy pulp, which in nature helps them to remain 

 moist until the rains begin. They are able to resist exposure to even 

 a moderateh T dry atmosphere for only two or three weeks, and if packed 

 together in any quantity they spoil even more promptly. The perish- 

 ability of the seeds has been a considerable obstacle in the planting 

 of "Castilla, and especiall}^ in its introduction into foreign countries. 

 The first shipment of 7,000 seeds secured by the government of British 

 India from Panama in 1875 was a total loss, and the introduction was 

 made by means of a few cuttings, carried around by way of England. 

 Later the Kew Botanical Gardens sent rooted cuttings also to Liberia 

 and to the Kamerun River settlements in West Africa, to Zanzibar, 

 Mauritius, Java, and Singapore, as well as to Jamaica and Granada in 

 the West Indies/' In 1880 the largest of the Ceylon trees was 17 inches 



«W. Thistleton Dyer, Trans. Linnaean Soc, London, 2d ser., 2:214, 1885. 



