55 



Fig. 2. Cross section of a pwre of Spruce wood, showing early stage of destruetion 

 by Trainctrs 2>>nl forma (thirds. Parallel lines of holes filled with cellulose fibers, here 

 indicated Ijy dots, appear in the wood. The black lines bounding the cavities siniplj^ 

 indicate the limit of change of cellulose, for in reality there is no such sharp line of 

 demarcation. The short line at the right equals about 25 of an inch (1™"'). 



Fk;. 3. Later stage of the same form of decay. The wood is now simply a network 

 of narrow wood lamelhe separating larger and smaller holes. In these lamelUe ]>lack 

 lines are shown, which represent plugs of brown hyphfe incrusted with decomposition 

 products. (See PI. IX, figs. 10 and 13. ) Cellulose fibers and mycelium fill some of the 

 cavities. The short line at the base equals about ^V of an inch (1'"'"). 



Fig. 4. Longisection of wood (Spruce), showing effects of destruction by hyphje of 

 Polyporus pinicola. 



Fig. 5. Cross section of several wood cells, showing changes which take ])lace in 

 wood such as shown in fig. 4. 



PLATE XL 



Fk;. 1. Tangential view of Spruce avoo<1 destroyed by mycelium of PoIi/jkh'uk snJ- 

 fureus (Bull) Fr. : "a" wood elements which have been curved, bringing two med- 

 ullary rays into line; " e" part where a break occurred, uniting two medullary rays. 



Fk;. 2. Radial view 01 wood in last stage of decay, induced by mycelium of Poli/- 

 jwnis Kiihitriilus Pk. The straight lilack lines represent one or more wood elements 

 held in i)lace by the hyplue wliich are wound all around them. Remnants of medul- 

 lary rays are to be seen here and there. 



Fk;. 3. Several cells from such a piece as is shown in fig. 2 (also PI. XIV, fig. 3). 

 Normal wood cells of the spring wood are shown at the left, and going toward the 

 right various stages in the solution of the cell walls. 



Fk;. 4. Tangential view of a piece of Spruce wood destroyed by mycelium of Poly- 

 porus sulfureus, showing characteristic breaks in the wood, formed by the uniting of 

 many medullary rays by cross breaks. (See fig. 1 of this plate.) The short line at 

 the left is equal to l'""'. 



PLATE XII. 



Various forms of sporophores of Tixnnck's phil forma abietis. 



Fig. 1. On Balsam Fir. 



Fk;. 2. On Tamarack. 



Fig. 3. On horizontal branch of Spruce. 



Fig. 4. On bark (jf trunk of Spruce. 



Fk;. 5. At base of dead branch of Spruce. 



Fk;. t). Semipileate form on Spruce. 



Fig. 7. At base of dead branch of Spruce. 



PLATE XIII. 



Radial view <if a lilock of White Spruce {PIrea rxiiftilrnsis (Mill.) B. S. P.) partly 

 destroyed by mycelium of J'n/i//)(triis sulfureus. The darker spots at one side show 

 where the wood turns brown and ultimately cracks. The manner in which the 

 annual rings sejjarate is indicated near the top of the figure. 



PLATE XIV. 



Fig. 1. Radial view of White Spruce {Picea ainadensis) , showing early stage of 

 destnu;tion by Polyporus suhncidus Pk. 



Fk;. 2. Radial vicnv of White Sjiruce log showing ilestruction of wood by mycelium 

 of Polyporus subacidus I'k. The white lines show where the wood has been so 



