DEVELOPMENT OF THE MUSHROOM. 11 



hole and form the bracket fruit body, in case the knothole or wound 

 has not completely healed over so as to imprison the fungus 

 mycelium. 



Fungi in Abandoned Coal Mines. Mushrooms and bracket fungi 

 grow in great profusion on the wood props or doors in abandoned 

 coal mines, cement mines, etc. There is here an abundance of 

 moisture, and the temperature conditions are more equable the year 

 around. The conditions of environment then are very favorable for 

 the rapid growth of these plants. They develop in mid-winter as 

 well as in summer. 



Mycelium of Coal Mine Fungi. The mycelium of the mushrooms 

 and bracket fungi grows in wonderful profusion in these abandoned 

 coal mines. So far down in the moist earth the air in the tunnels 

 or passages where the coal or rock has been removed is at all times 

 nearly saturated with moisture. This abundance of moisture, with 

 the favorable temperature, permits the mycelium to grow on the 

 surface of the wood structures as readily as within the wood. 



In the forest, while the air is damp at times, it soon dries out to 

 such a degree that the mycelium can not exist to any great extent 

 on the outer surface of the trunks and stumps, for it needs a great 

 percentage of moisture for growth. The moisture, however, is 

 abundant within the stumps or tree trunks, and the mycelium 

 develops abundantly there. 



So one can understand how it is that deep down in these aban- 

 doned mines the mycelium grows profusely on the surface of doors 

 and wood props. Figure n is from a flashlight photograph, taken 

 by the writer, of a beautiful growth on the surface of one of the 

 doors in an abandoned coal mine at Wilkesbarre, Pa., during Septem- 

 ber, 1896. The specimen covered an area eight by ten feet on the 

 surface of the door. The illustration shows very well the habit of 

 growth of the mycelium. At the right is the advancing zone of 

 growth, marked by several fan-shaped areas. At the extreme edge 

 of growth the mycelium presents a delicate fringe of the growing 

 ends where the threads are interlaced uniformly over the entire 

 area. But a little distance back from the edge, where the mycelium 

 is older, the threads are growing in a different way. They are now 

 uniting into definite strands. Still further back and covering the 

 larger part of the sheet of mycelium lying on the surface of the door, 

 are numerous long, delicate tassels hanging downward. These were 

 formed by the attempt on the part of the mycelium at numerous 

 places to develop strands at right angles to the surface of the door. 

 There being nothing to support them in their attempted aerial flight, 



