THE POLYPORA.CEAE OF WISCONSIN. 7 



Fomes carneus was found abundantly on logs of white pine, spruce 

 and tamarack. No specimens were found on living trees. One small 

 distorted specimen was found on the under side of an arbor vitae log. 



In a small area of less than an acre in the Yawkey Lumber Com- 

 pany's stand there were twelve red pine and two white pine trunks 

 which showed numerous pilei of Polyporus volvatus Pk. growing out 

 through the bark. Two of these trees (red pines) were living. A few 

 had apparently been dead several years while most of them had been 

 killed by a fire the year before. Near Lake Catharine was a large 

 living white pine which showed several pilei of the same fungus. 

 Whether this fungus ever causes the death of trees was not deter- 

 mined. It is possible, however, that it does have some effect upon 

 the wood, especially in the immediate neighborhood of the holes pro- 

 duced by bark borers, out of which its pilei seem almost always to 

 grow. Still, the mycelium sometimes spreads under the bark and 

 this may be sufficient to injure the tree. 



In their abundance and relative destructiveness to timber the spe- 

 cies show a wide range of variation. I shall next describe in more 

 detail those forms which in the region studied were evidently of the 

 greatest economic importance in destroying the living or dead trunks 

 of the more valuable timber trees. 



Polystictus abietinus (Dicks) Fries. 



This fungus looks very much like Polystictus pergamenus in color, 

 shape, habit, and pores, but the latter grows only on deciduous trees, 

 while the former grows only on the conifers. The zones are often 

 quite distinct as concentric sulcations. The pores are larger than 

 those of P. pergamenus, but shallower. When growing the pores 

 are violet and they retain much of this color in drying. When old, 

 the hymenium becomes torn into teeth and the pileus becomes more 

 and more incurved. Trees are often covered from the ground up- 

 ward for from twenty to fifty feet with the pilei which grow out 

 through the bark. 



Infection takes place through wounds. In all the trees examined 

 that were infected with this fungus it was perfectly plain that the 

 entrance of the fungus was through a wound. The pilei are found 

 growing out of the region of the trunk where the tree was wounded, 

 and from this region as a center, they spread, appearing successively 

 in some cases for fifty feet or more up and down the trunk. They 

 are found on trees of all sizes and ages whenever there is an opening 

 through the bark made so that the spores can gain an entrance. Oc- 



