DECAY OF THE " BLUE " WOOD. 29 



the Black Hills Forest Reserve where the beetle attack took place some 

 four or more years ago there are thousands of dead trees standing with 

 their tops broken off much like- those shown in Pi. XII. In this view 

 the tops can be seen tying on the ground. PL XIII, fig. 1, shows the 

 lower end of one of these tops. One will note how sharp it has broken 

 off almost straight across. One of the sheets of mycelium has curled 

 over at the extreme right of the figure. The cross sections of such a 

 top (reproduced on PL XI, figs. 1 and 2) show how completely the wood 

 has been destroyed and that there is small chance for such a top remain- 

 ing on the tree very long. 



Where the u red-rot" fungus attacks the tree at its base it brings 

 about the decay of the larger roots underground, and also of the sap- 

 wood of the trunk close to the ground (PL VI, fig. 2, large section, 

 and PL XI, fig. 3). After a time the roots become weakened to such 

 an extent that they are no longer able to keep the trunk in an upright 

 position, and the result is that the tree is blown over. Such a fallen 

 tree is then attacked rapidly at all points by the "red-rot" fungus, 

 and in a few years nothing is left of it but a pile of rotted wood. 



When the wood has been completely destroyed the fruiting organs 

 of the " red-rot" fungus begin to form. Some of the hyphse grow out 

 through the bark and form a flesh-colored knob (PL XI, fig. 1), which 

 rapidly increases in size and turns reddish in color. This knob grad- 

 ually widens horizontally, forming a shelf, and on the lower side of 

 this shelf numerous pores appear. One of these bodies is seen grow- 

 ing out from the fallen top shown on PL XIII, fig. 1, a little below 

 and to the right of the small branch extending out toward the front 

 of the picture. (See also PL XI, fig. 2, and PL XIII, fig. 2.) After a 

 year a mature fruiting body or sporophore (commonly called a punk, 

 mushroom, or toadstool) has developed, from which spores are dis- 

 charged at intervals. These spores are formed in the small tubes 

 found on the lower side of the sporophore, and on a quiet night one 

 can see them coming from the sporophore in white clouds as they are 

 being discharged in countless thousands. The spores are so light that 

 they are carried many miles by the winds and lodge on every stick and 

 tree in the vicinity. 



The sporophores of this fungus may grow for many years. At dif- 

 ferent periods, the length of which is not yet definitely known, they 

 add a ring on the outside and thereby increase in size. The one shown 

 attached to the section on PL XI, fig. 2, is probably 2 years old, while 

 the one at the base of the tree on PL XIII is probably several years 

 old. The sporophores may occur singly or in groups of two or three 

 together. When a top falls so as to lie close to the ground where it 

 is likely to be kept wet, the sporophores will develop every few inches, 

 so that there may be as many as 20 or 30 on a log 10 feet in length. On 



