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The special part, in which the pests of Hevea braziliensis (Para), 
Ficus elastica (Rambong), Castilloa elastica, Kickxia elastica , and 
Manihot Glaziovii (Ceara) are detailed one by one is preceded by an 
interesting introduction in which the author advances some general 
considerations on plant disease, and complains incidentally of the bad 
condition in which material sent in for identification is received. He 
says that during the past two years planters have frequently sent 
to the Department of Agriculture at Buitenzorg specimens of rubber 
plants attacked by diseases more or less serious. Unhappily the 
material, being for the most part badly packed and having been for a 
greater or less time in over-heated waggons or in store-rooms, arrived 
in such a bad state that it was impossible to make a serious examina- 
tion of it or to give the real cause of the injury done ; the humid warm 
atmosphere which surrounded the plants favoured the devolopment of 
a crowd of organisms among which it was impossible to distinguish 
the originator of the disease. 
“ It is necessary in the first place to give a few recommendations, 
which may appear common-place, or at least elementary, but on 
which it is nevertheless good to insist and which are important to keep 
before one’s mind when occupied with plant disease- 
It is not necessary, I think, to delay long on questions pertaining 
to soil, drainage or manure. I have occasionally seen a soil, excellent 
in outward appearances, which at a depth of a foot or so changed its 
constitution and became for example clayey and damp. This may be 
serious in the case of plants with a tap root such as Hevea ; when the 
root reaches the wet layer of soil, it will be in a condition to rot and 
to become a source of disease. Enough account is not always taken of 
the richness of the soil in nutritive substances. I have been able to 
demonstrate several instances of plants becoming the prey of various 
parasites, because the soil having been previously exhausted by long 
cultivation the plants were debilitated and had not the force to resist 
their enemies. 
I wish to insist on a knowledge of the importance of proper 
surveillance and of the immediate notification to competent persons of 
the least appearance of unhealthiness among the plants, whether it may 
appear serious or mild. This recommendation is important for rubber 
plants. Their cultivation is not yet very extensive in -Java, or at least 
has only developed within the last few years ; but as it has made 
remarkable progress it is necessary to give it the greatest attention. It 
is much easier to protect a cultivation in the way of formation against 
its enemies, than to save old plants from parasites whicli have multi- 
plied at their convenience on account of special circumstances. 
Diseases of Hevea braziliensis. 
(a). Corticiuni javanicum, Zimm. This appears to be the most im- 
portant disease of Hevea. The parasite is well known from the havoc it 
has caused among coffee, where it attacks the stems and fruits. 
Zimmermann, who discovered it on Hevea, attached great importance 
to it, and proved that it is a true parasite which kills the branches 
which it attacks. During the past two years I have studied several 
cases where the parasite brought about the death of the plant. 
