130 THE BOOK OF NATURE STUDY 



Its cap resembles a bun, the upper surface being brown and 

 glazed, the tubes are greenish, the stout stalk shows a network 

 of fine lines (especially near the top), and the white flesh does 

 not change colour when cut or broken. The Lurid Boletus, 

 said to be poisonous, has a velvety dark brown cap, deep 

 red pore surface, and red or yellow stalk, and its yellowish 

 flesh turns deep blue instantly on being broken or cut across. 

 All pore toadstools which change colour when cut or broken are 

 unwholesome. 



The Bracket Fungi grow on the stems of dead or living trees. 

 One of the commonest is the Birch Polypore, which is found 

 on living and dead trunks and branches of birch from spring 

 to early winter. Its fruit is hoof-shaped, brownish, and corky, 

 with a layer of short tubes on the under side. It is sometimes 

 called the " razor-strop fungus," thick slices cut from it being 

 used for this purpose. The rest of the fungus grows inside the 

 bark of the tree, forming extensive leathery sheets which consist 

 of densely matted threads. Like several other kinds of bracket 

 fungi, it may cause great damage in woods and plantations. 

 The spores are carried about and settle in wounds on the trunk, 

 where branches have been broken off and where rain-water has 

 collected. There they sprout and, entering the living wood of 

 the tree, spread rapidly and simply eat away the inside of the 

 trunk and reduce the hard wood to a soft spongy mass which 

 crumbles when touched. When a tree is attacked by the bracket 

 fungus its leaves turn yellow and die off, then the lower part 

 of the stem begins to die and becomes rotten, though the bark 

 appears unaffected. 



To illustrate the extreme thoroughness with which the threads 

 of a bracket fungus attack the wood of the tree it has lodged 

 in, the late Professor Marshall Ward described a block of diseased 

 timber which was sawn across and showed a number of brown 

 egg-shaped bodies embedded in the closely woven felt (the 

 fungus body). These bodies are simply the shells of so many 

 acorns, embedded in and hollowed out by the fungus. Evidently 

 a squirrel had stored up the acorns in a hollow in the tree and 

 had not returned to them, what tragedy intervenes must be 

 left to the imagination. The polypore had then invaded the 



