38 



where the spores of this fungus find a most suitable place for entrance 

 into the trunk. The spore germinates and the m3'celium grows down 

 through the dead heartwood of the branch. From there it spreads 

 through the heartwood of the trunk, growing both up and down. The 

 growth in these directions takes place more rapidly than the lateral 

 growth. When the sapwood is reached, the progress is a slow one, 

 owing to the resinous contents. At about this time the sporophore 

 begins to form. The wood of the callus and the living sapwood of the 

 knob become so thoroughly impregnated with turpentine that the 

 mycelium does not grow in them, but grows out through the dead 

 wood of the branch. At the first point where the hyphse can reach 

 the air without haA'ing to go through the collar of sapwood they 

 emero-e. Where the dead branch has broken off close to the callus the 

 hj'pha? grow out from the stub and form a cushion on it. More 

 frequently, however, the red-brown cushion is formed at the point where 

 the living callus touches the dead wood (PI. XII, fig. 6). The cushion 

 is at first very small and looks as if covered with velvet. The hyphse 

 rapidly grow radially and form a sheet which adjusts itself to the 

 shape of the callus and branch. At the edges this sheet projects from 

 the bark and forms an irregular shelf, the top of which after a time 

 becomes zonate and brown-hairy, as in the more strictly bracket-like 

 forms. On many old Spruces there are deep clefts between the vari- 

 ous bark scales, and in them sheets of the sporophores form whose folds 

 fill the crevices completely, forming pores on the outer surface of the 

 newer bark and the inner surface of the old scale. Growth takes place 

 rapidly during the latter part of summer and early fall so far as could 

 be noted. The hyphjB at the edge extend the area of the sheet, while 

 those forming the walls of the pores grow vertically downward. 

 Within the pores many hypha? grow into the holes, so that after a 

 3"ear or two these are completely plugged at the base. There are at 

 present no means of judging how old one of the sporophores described 

 may orow to be. The oldest one found was about four-fifths of an 

 inch {2"") in thickness. 



Trametes pi7ii forma ahletis was found ])ut rarely on the Fir. Its 

 sporophores assume on this tree a different haliit from those on the 

 Spruces. On vertical surfaces a distinct sessile pileus is formed, 

 resembling a ])racket, rather than a hoof, as do those on the Spruce. 

 The mycelium, after having grown throughout the heartwood, grows 

 into the sapwood, where it flourishes much more vigorousl}" than in 

 the Spruce because of the absence of resin. From the sapwood the 

 hyphie enter the bark and break through it all over the trunk. At 

 the points where they emerge they form small cushions, light red-brown 

 in color, which are at first the size of a pin head, but rapidly increase 

 in size (PI. XII, fig. 1). When barely /g of an inch (2 '"■") in width, a 

 differentiation into an upper and lower surface takes place. A band of 



