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Rh cases: some of the fungi destroy the vessels, fibers, etc., by dissolving their walls from inside, while others destroy the part common to contiguous cells, etc., and thus first isolate the elements and then complete the destruction. A series of very interesting researches by



Hartig has demonstrated that the presence of these timber-destroying fungi can be detected from the markings and discolorations they produce in the wood; those due to Hydnum diversidens, Thelephora Perdix, Polyporus sulphureus, P. igniarius, P. dryadeus, and Stereum