455 



It is clear from these experiments that stirring the seeds round 

 in the liquid, whether water or copper sulphate solution, is extremely 

 injurious. 



The best disinfectant results as far as germination is concerned 

 appear to be from the use of bichloride of mercury in weak solution, 

 and washing afterwards without stirring the seeds round. 



This solution might, however, not be strong enough to thoroughly 

 disinfect the seeds, assuming they were covered by spores. 



Personally I think the risk of importing seeds with spores of rub- 

 ber-killing fungi is infinitesimal. Supposing, for instance, one rubbed 

 a seed with spores of Fomes and planted it in the nursery. The 

 spores would not last indefinitely and it would be probably two years 

 before the plants in the nursery would be old enough to be attacked. 

 It is in the highest degree improbable that any of the spores would 

 germinate at all under the circumstances. In the case of Diplodia 

 the risk would be still smaller, as Diplodia requires to be put on the 

 cut end of a shoot to make a successful growth. As I have pointed 

 out till decomposition of the exterior of the shell of the seed sets in 

 the spores could hardly rest on the smooth surface, and would even, if 

 attached by mud etc., or included in the packing, be washed away by 

 ordinary plunging in water and probably by the first rain also. 



The case is quite different with stumps or plantlets infected being 

 brought into the estate. Here the fungus is established in a thriving 

 state on the young plant, and can go on developing there. It is put 

 in contact with healthy plants in the same conditions of life perhaps 

 even thumb-nail pruned or with buds wounded in some away. By 

 planting infected spore producing plants in such a healthy lot, a 

 planter would be putting the fungus in the best possible position for 

 its development. 



The fungi belonging to the group Polyporei are extremely abundant 

 all over the tropics and it is very unlikely that Fomes semitoslus is 

 the only one that can adapt itself to attack Para rubber. Indeed we 

 know that Irpex flavus which used to give trouble with coffee can 

 attack Para rubber. Tubenf records thirty species of Polyporei as 

 fatally attacking trees in Europe and North America in the same way 

 as Foifics has taken to attacking Hevea, and as far as one can see any 

 at least of the larger Polyporei in the Tropics could adapt themselves to 

 attack Hevea. In Christmas Island I and others collected eleven 

 species of Polyporei, and there are probably a great many more to be 

 found in wetter seasons. How did these get to this isolated island ? 

 Some at least by spores blown for 250 miles from the nearest land, but 

 a number of the wood-destroying fungi were undoubtedly brought in 

 planks, poles, firewood, old boxes, etc. It is absolutely impossible to 

 prevent this. A bit of firewood on arrival at the port is found to be 

 rotten, i. e., it contains mycelium. It is naturally thrown away, 

 the mycelium continues to grow, and produces its sporophores. 

 Other rotting timber is lying round its spores attack that and 



