54 SEVENTH REPORT. 



except that some of them are stipitate, and a comparison of the specimens collected with 

 those in the University collection labeled Pohjportis lucidus shows marked differences, in 

 color, general appearance, character of margin and of pores. The bands of color are ex- 

 actly as described for G. sessile. The margin is very thin and acute, curved somewhat 

 downward in one specimen. The pores are more irregular, often larger, and the dissepi- 

 ments thinner than in Polyporus lucidus Fr. If the specimens are Ganoderma sessile the 

 description of that species ought to include stipitate forms. If they are merely varia- 

 tions of G. pseudoboletus (Polyporus lucidus), it would seem that G. sessile is not a well 

 marked species. 



The specimens from Allen's woods were growing in very moist ground, and were them- 

 selves very wet at the time of collecting, so that considerable water could be squeezed out 

 of them. They were very pliant, but quite tough. After drying they are hard and woody. 



As to the parasitism of this fungus, the evidence is not conclusive, since it was not pos- 

 sible to determine by external observation alone how far the maple tree mentioned was 

 affected. If the tree dies and is removed an opportunity to do this will be given. When 

 the fungus was found in fruit on the base of the trunk and also on the ground in the direc- 

 tion toward the nearest walk, it suggested the thought that here was a wound parasite, 

 which had gained entrance to the host at the point where the roots were cut off in laying 

 the nearest walk, had progressed along the root to the base of the trunk, and had pro- 

 duced its sporophores at the base of the trunk as well as from the infected root. The 

 sporophores in the latter position being the stalked forms, since the root was under ground 

 and in a horizontal position. The stalk of one was followed into the ground for three or 

 four inches, but could not be followed as far as a root, nor did it seem to run out laterally 

 into mycelial threads. It seemed to mix with the soil and be indistinguishable from it. 

 On the base of the trunk the sporophore was very closely attached by a broad surface, 

 and had to be cut off with a knife. The bark seemed to l)e permeated by the mycelium, 

 but no attempt was made at the time of collecting the fungus to determine the extent of 

 injury to the tree. 



At the present writing (April, 1905) the tree is still alive, as the buds are swelling pre- 

 paratory to opening, but a close examination of the trunk shows an area of dead bark, 

 taking the form of a narrow triangle with its base at the point where the sporophore was 

 produced, and its apex about one meter above. This triangle is only a few decimeters 

 wide at the widest part, and its exact limits were not determined for its whole boundary. 

 The bark is dead, brown and brittle down completely to the wood. The cambium is dead 

 also. The outer layers of wood however are solid and apparently uninjured, and "bleed" 

 at the slightest knife cut. On neighboring parts of the trunk the inner layers of bark 

 are light colored, fresh, tough, and with all the appearance of being alive. 



On looking for possible points of infection on the trunk, two were found that need men- 

 tion. One was a small area of exposed dead wood about thirty-five centimeters from the 

 ground, not far from one side of the triangle of dead bark mentioned above. This was 

 surrounded by a healthy growth of bark, which was of several years growth and had 

 almost closed over the old wound. There was no evidence that this had served as the 

 point of infection for the triangle of dead bark, since they were separated by several inches 

 of healthy bark. The other possible point of infection was a dead stump of a branch not 

 yet closed over by growth, about three meters aljove ground, and directly above the ver- 

 tex of the triangle of dead bark. Here again, however, there was a long space of healthy 

 bark, about two meters of it, between the dead stub and the triangle. Hence there was 

 no reason for supposing a connection between the two. 



Taking into consideration the location of the triangle of dead bark and the shape, it 

 is reasonable to conclude that the cause of death started at the base, where the sporophore 

 of Ganoderma sessile had been found, and progressed upward to the vertex of the triangle. 



It becomes probable then that this fungus is a parasite, and perhaps the cut roots be- 

 came the point of infection, while the reduced vitality and vigor brought about by the 

 loss of water made the tree an easy victim for the fungus. 



To sum up: Ganoderma sessile has stipitate as well as sessile forms, and this fact should 

 be recognized in the description. It developed three sporophores in one spot during the 

 same season, in July, in August, and September-October. 



It is probably a wound parasite, destroying the bark and cambium, but not the living 

 wood. 



The last point needs further confirmation, and observations will be continued on the 

 tree for future developments. 

 University of Michigan. 



