HEART-ROT CAUSED BY OTHER FUNGI 141 



tion in this country. Rostrup (1902) does not include it 

 among Danish fungal diseases. In India it occurs on Pinus 

 excelsa (Mayes, 1905). 



The fructification of the fungus is of Polyporus form, and 

 may be composed of either a single large bracket (up to 

 9 in. wide), numerous imbricated small brackets, or ' re- 

 supinate ' incrustations which may spread for 10 ft. or 

 more on the under -side of branches or fallen trunks. It is 

 hard, woody, and perennial, and is most easily distinguished 

 by the light red-brown colour of the lower surface, which 

 is pierced by small pores. The pores are round, but appear 

 elongated where the surface is not horizontal, a feature, 

 however, which the fungus has in common with many 

 allied species. Brackets are produced freely on dead trees, 

 and the spread of the fungus is chiefly secured by these 

 post-mortem growths. The hymenial surface which lines 

 the pores bears basidiospores which are 5-6X3-4 ju, and 

 is characterized by elongated, brown, pointed, thick- walled, 

 spine-like paraphyses or ' cystidia ' not unlike those figured 

 in Polyporus Schweinitzii. They persist in the pores for 

 a long time after the region bearing them has .ceased to 

 produce spores. 



The process of decomposition induced in the wood by 

 the fungus has been described by Hartig (1878) and Schrenk 

 (1900). From the infected branch narrow red-brown streaks 

 spread both upwards and downwards in the trunk. Though 

 these streaks scarcely spread at all in a radial direction, 

 they may become tangentially extended in the annual ring 

 or rings in which they were initiated, and in this way 

 produce a kind of ring-shake in the tree. Several partial 

 rings of this nature may arise before the centre of the tree 

 is appreciably affected. The wood outside the red-brown 

 area becomes suffused with turpentine and resin, which to 

 a considerable extent limit the spread of the mycelium. 

 White flecks then appear in the red rot portions, which are 

 occasionally, but by no means always, preceded by black 

 spots similar to those caused by Fomes annosus. These 

 flecks are much larger than those produced by F. annosus, 



