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Hemileia Vastatrix

filaments, disease and leaves

HEMILEIA VASTATRIX, the coffee-leaf disease, or leaf-fungus, has for several years seriously affected the coffee trees of the island of Ceylon. Though requiring careful inspection for its detection, it was present upon all the coffee trees examined about 1879. With the help of the microscope, it is found at all times to pervade the greater part of the stems and older leaves, in the form of very fine branching filaments, its effects being apparent in numerous somewhat translucent spots, which may be observed when holding one of the older leaves against the light. The injury so caused to the coffee tree is, however., very slight, as compared with the effect produced when the fungus attacks the young leaves, causing them to fall prematurely. The presence of the fungus-filaments in such abundance` on the outer 3nrfaco of the tree is quite sufficient to account for phenomena which it was first thought must be attributable to a poisoning of the juices of the tree, by an absorption of the fungus matter through is roots. The latter idea must therefore be given

up, and the disease considered as external, except when it appears within the tissue of the young [eaves. Subsequently, from these enclosed masses )f filaments short branches arc produced, which ;merge from the pores, and bear the conspicuous wange-coloured spores or reproductive bodies. 3onie of these spores have been observed to 4.erminate on the outside of the leaf, producing >ranched filaments of exceeding tenuity, which ;row with marvellous rapidity all over the:surface A the leaf, and beyond to the sterns. The ends A some of these filaments, too, have been observed o enter the pores of the leaf, to form fresh disease pots and fresh crops of spores. 'rite true Liberian ;offee is said to be of hardy habit, and more able o resist the ravages of this disease.