III2 



Home Nature-Study Course. 



of the tree trunk, and kill the tree entirely; but the tree may live many years before 

 this is accomplished. Professor Atkinson found one of these bracket fungi that 

 was eighty years old. This, may have shortened the life of the tree a century or 

 more. 



After these fungus threads are thoroughly established in the tree, they again 

 seek a wound in the protecting bark where they may push out and build the 

 fruiting organ, which we call the bracket. This may be at the same place where 

 the fatal entry was made or it may be far from it. The bracket is at first 

 very small and is composed of a layer of honeycomb cells, closed and hard above 

 and opening below; cells so small that we can see the cell openings only with a 



The edible Boletus (B. ediiUs). This has tubes below the cap instead of 

 gills. The spores are developed within the tubes. 



lens. These cells are not hexagonal like the honeycomb, but are tubes packed 

 together. Spores are developed in each tube. Next year another layer of cells 

 grows beneath this first bracket and extends out beyond it : each year it is 

 thus added to, making it thicker and marking its upper surface with concentric 

 rings around the point of attachment. The creamy surface of the great bracket 

 fungus, on which etchings are made, is composed of a layer of these minute spore- 

 bearing tubes. Not all bracket fungi show their age by these annual growths, 

 for some species form new shelves every year which decay after the spores are 

 ripened and shed. 



When once the mycelium of such a fungus become established, the tree is 

 doomed and its lumber made worthless even though, as sometimes happens, the 



