Les maladies et ravageurs de l'arbre à caoutchouc . t à, souvent irrégulières et composé de plusieurs ensemble. bracketsfused Les supports séparés sont trois ou fourinches large, et environ un tiers de pouce d'épaisseur, et veryhard. La surface supérieure est généralement brun-violet, allié-concentrique cannelé, et glabre. La surface inférieure est brun foncé presque noir,ou lorsqu'ils sont humides. Lorsqu'il est brisé en deux seento se composent d'un disque dur, sombre, l'écorce terrestre, avec des browntissue à l'interne. Le spécimen figuré (planche II, fig. 9)est un brun plus pâle que d'habitude. Le tissu interne une usuallyshows zonage concentrique, w

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The diseases and pests of the rubber tree . t-shaped, often irregular and consisting of several bracketsfused together. The separate brackets are three or fourinches broad, and about one-third of an inch thick, and veryhard. The upper surface is purple-brown, usually concentric-ally grooved, and glabrous. The lower surface is dark brown, or almost black when moist. When broken in two it is seento consist of a hard, dark, outer crust, with lighter browntissue internally. The specimen figured (Plate II., Fig. 9)is a lighter brown than usual. The internal tissue usuallyshows a concentric zoning, with curved transverse linesparallel to the margin. The pores or tubes on the undersurface are lined with setae, similar to those which occur onthe supposed Hymenochaete patches. The fructification ispeculiar in that its internal tissues are built up of two kindsof hyphae, the one thin-walled, like fungus hyphae in general, the other thick-walled and resembling the setae in structure.The name of this species is Fomes hmaoensis. It frequently. ^J!^—? ROOT DISEASES n ROOT DISEASES 49 occurs in resupinate form, i.e. lying flat on the root orstem. The discovery of the Fomes fructification clears up thedifficulty of accounting for the distribution of the disease.It is now evident that infection can be conveyed by wind-borne spores from the fructifications on decaying stumps ortimber in the jungle or elsewhere. But in Ceylon the fructifi-cation is by no means common, and it would seem that specialcHmatic conditions are required for its development. In illustration of the rate at which the disease spreads thefollowing instance may be cited. Hevea was planted, 14feet apart, in a single line round the boundary of an old-established Cacao estate. When the trees were eight yearsold one of them died, from Brown Root disease as wassubsequently discovered. The tree was left standing andallowed to decay. Two years later the next tree in the linedied and was likewise left to decay. After a fur

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