The Polyporaceae are a group of most interesting fungi which have of recent years assumed a position of prime economic importance as it has been demonstrated that many of them cause the decay of timber trees which formerly they were supposed to follow. The parasitic nature of these fungi has added a new incentive to their careful study. Some species are found only on the diseased portion of living trees, while others appear to inhabit only dead timber. Of these it is not improbable that a considerable number may be able to infect living timber and later to maintain themselves on the wood as long as those portions remain which furnish them with their food
