Cxxxvii. the Chemistry of the White Rots of Wood. I. the Effect on Wood Substance of Polystictus Versicolor (linn.) Fr

INTRODUCTION. THE somewhat arbitrary classification of the wood decays caused by fungi into " brown " and " white " rots has in recent years been the subject of controversy, as it has been suggested that more accurate classification can be based on strictly chemical evidence regarding the effects of the various wood-rotting fungi on wood substance. So far as "brown" rots are concerned a sufficiently representative number of these would appear to have been studied in order to make it possible, within the limits of available knowledge, to assign a hitherto unstudied fungus to this class on chemical grounds alone, for it has been shown that the chemical effects of " brown " rots on wood substance can strictly be compared to those of simple aqueous acid hydrolysis [Campbell and Booth, 1929]. The specificity of fungi generally with regard to time, mode and position of attack, together with the important question of host selection, has been postulated as a cogent factor in support of the view that the ultimate chemical effects of fungi on wood may be so variable as to preclude the accurate classification of decay into types on chemical grounds. Having in mind, however, the general composition of the, skeletal substance of wood and its comparative chemical uniformity throughout the wide range of hardwoods and softwoods for which analytical data have been obtained, it is conceivable that, apart from climatic and other external conditions, the selective capacity of wood-rotting fungi must be controlled largely by the presence or absence in specific woods of substances, other than wood substance proper, which are toxic or otherwise intolerable to certain fungi. This is borne out by the work of Hawley, Fleck and Richards [1924], and of Sowder [1929], and is generally accepted as the explanation of the immunity to decay of notably durable woods. In this connection attention is directed to the conclusionis arrived at by Rege [1927] and more recently by Norman' [1929, 1] in their estimates regarding the "decomposability" of cellulosic