8 THE POLY POR ACE AE OF WISCONSIN. 



easionally the pilei grow out of holes made by bark borers. One 

 spruce tree in a swamp near McNaughton had been barked for an 

 area four feet long and from three to five inches in width, by the 

 felling of a pine tree nine years before. On this wound numerous 

 pilei were growing. A few scattered pilei were growing also out of 

 the bark above this wound for a distance of twenty feet. Wood 

 specimens were cut out as far as the pilei extended and the charac- 

 teristic decay of the wood was evident. We have thus the evidence 

 as to the rate at which the fungus spreads when once it gains a foot- 

 hold in a tree. The remainder of this tree was alive and the top 

 comparatively thrifty. In all, seven living trees were found in- 

 fected whose tops indicated a greater or lesser degree of thrift, 



Near Carr Lake a red pine stump was found infected with this 

 fungus. The tree, which was perfectly sound and healthy, had been 

 cut the year before. On one side, the wood had been somewhat 

 slivered by the felling of the tree. Here infection took place. This 

 infection was only one year old and minute pilei were just forming, 

 no rot was noticeable to the naked eye. The mycelium that was 

 growing out of the wood and bark to form pilei was white and 

 velvety. It was plain that the first three rings of growth con- 

 tained mycelium since it was out of these rings that the pilei 

 were growing. Infection seemed to have taken place in the side 

 through the split surfaces and not from the top through the sawed 

 surface of the wood. This white cottony mycelium was also found 

 spreading under the bark to some extent. 



Infected dead trunks both standing and prostrate are abundant 

 in some areas. This is especially true in exposed parts of the for- 

 est, viz., near the edges of the forest bordering on clearings or the 

 shores of the lakes. In these places, there are many wind-felled 

 trees lying in different directions and many cases of wounding can 

 be traced to the falling of these trees. This probably accounts for 

 the abundant infections in such localities. In an area of about an 

 acre between Little Tomahawk and Carr Lake, thirty to thirty-five 

 standing trunks were found infected out of a total of one hundred 

 and twelve trees, besides many prostrate trunks. All of these were 

 hemlocks with diameters varying from eight to fifteen inches. These 

 trees were especially exposed t,o winds from two directions. I cut 

 one tree about eleven inches in diameter and one hundred and fifty 

 years old to determine the extent to which the wood was affected. 

 The pilei were found present to the very top, which was dead. 

 About thirty feet from the top there were about half a dozen living 

 branches. On the side on which the living branches were found. 



