The Hawaiian forester and agriculturist . e macrospores. It is not often, inall probability, that the disease is transferred from one hostto another by means of the mycelium. The microscopic appearances of the various parts of thisfungus are well shown in Fig. 4. The mycelium, atfirst colorless, becomes at last light to dark brown, thoughnever of the latter color except in the fully decomposedtissues of the heart of the cane. In the partly discolored andthe reddish tissues associated with the onset of the disease themycelium is nearly always colorless. The mycelial cells arefrom three to ten o
The Hawaiian forester and agriculturist . e macrospores. It is not often, inall probability, that the disease is transferred from one hostto another by means of the mycelium. The microscopic appearances of the various parts of thisfungus are well shown in Fig. 4. The mycelium, atfirst colorless, becomes at last light to dark brown, thoughnever of the latter color except in the fully decomposedtissues of the heart of the cane. In the partly discolored andthe reddish tissues associated with the onset of the disease themycelium is nearly always colorless. The mycelial cells arefrom three to ten or more times as long as broad, and contai:irefractive bodies, more particularly in the neighborhood of thespore-bearing branches. It varies in thickness from three toeight micromillimetres, and is extensively branched, the longerbranches naturally lying in the same direction as the axis of thecane. APPEARANCE OF THE SPORES. The thin-walled microconidia, which germinate so easilyand hence serve to spread the disease rapidly, are formed in. Fig. 4. Mycelium of the fungus causing Pineapple Disease, Tliii>:sethaceticus. This mycelium is abundant in the pinkish, reddish, brownish ardblack tissues of cane attacked by this disease. It is a well characterized myceliumand it is possible to identify it with some degree of certainty, esoecially bymeans of the following test: If the fresh tissues containing the mycelium be cutopen and exposed over night to the air in a moist situation, the mycelium rapidlyproduces the dark colored macrospores charactertistic of this fungus. The larger figures are taken from a hanging drop culture, while the figures inthe rectangle .in the upper right hand corner are taken from specimens foundamong cane tissues. Two spores are shown to have germinated in the hang-ing drop culture and to have begun the production of chains of microspores asdescribed in the text. Above may be seen a chain of the darker colored micro-spores mentioned in the text. T
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