WOODS AND THEIR DESTRUCTIVE FUNGI. 441 



moisture accumulated where it rested on the joists, the mycelia work- 

 ing upward and each way, usually leaving a thin portion of one eighth 

 to one fourth of an inch in thickness, on the under side of the plank, 

 where exposed to the air, giving the appearance that it was all sound. 

 The abundant fructification during a brief warm rain in September, 

 1883, was the first indication of the destruction which had taken place. 



The upright cells or tracheids composing the annular ring of the 

 JPinus palistris (Mill) are of two kinds one of thin and the other of 

 thick walls ; the former fill the inner part of the ring, the latter the 

 outer portion, giving the great strength and hardness characteristic of 

 this wood ; interspersed through the ring are a few resin-ducts. In 

 decay induced by its special fungus, the mycelium often separates 

 some of the annual layers, and in most cases the thin-walled cells are 

 first softened. Driving spikes into railroad-ties of this wood breaks 

 and loosens the layers, and facilitates the entrance of the mycelium, 

 and then larvae, from one sixteenth to one eighth of an inch in length, 

 eat and bore in the large softened tracheids, leaving the harder ones, 

 so that in ties of four to seven vears' service we often find little more 

 than a series of nearly separated shells. The mycelium of this fungus 

 once in a road-bed lives for some time, and in summer is ready to 

 attack new ties of this timber as soon as put in the ground. I have 

 noticed ties taken up, after a short service of six to eight months, 

 which were covered on the bottom by the branching mycelium, and 

 after drying one eighth to one fourth of an inch in depth would crum- 

 ble to dust. It takes much longer for the mycelium to destroy the 

 heart-wood of the yellow-pine sleepers from the bottom and sides than 

 when it has access to the ends. In the first case it must nearly destroy 

 the small medullary cells to reach the various rings, while from the end 

 it has a larger area of the rings, which it readily follows. Painting 

 the ends of this timber offers but little protection if the slightest open- 

 ing occurs, as a spore can enter, grow, and carry on its destruction for 

 a long time before it shows exterior decay. 



The mycelium of Lentinus lepideus (Fr.) is composed of small 

 branching filaments, only measuring 0*0004 of an inch to 0*0008 of an 

 inch in diameter. With it I generally find an abundance of crystals 

 of one form of oxalate of lime, and many cells of other fungi in ad- 

 herent masses. The destructive power of this fungus is very great, 

 and is causing enormous losses to consumers of the yellow pine, which 

 are not realized or even suspected. In the sap-wood of this timber 

 the fungus Sphceria pilifera (Fr.) readily grows, piercing the resin- 

 ducts in the medullary rays, its hyphse spreading to the upright resin- 

 canals, and, from its abundance and dark color, discolors this portion 

 of the wood ; which, if it remains damp and warm, the fermentation 

 set up soon destroys the sap-wood. This fungus grows at a very low 

 temperature, and is very destructive. 



In new railroad-ties of yellow pine, which came from Georgia 



