352 Transactions British Mycological Society. 



3. Wood when attacked by this fungus becomes light, very 

 soft and paler in colour. The less lignified spring elements are 

 the first to disappear. 



4. Sporophores of this fungus which have been dried for a 

 considerable time when moistened shed spores which will ger- 

 minate, moreover the mycelium can be dried for many months 

 and still retains its vitality. 



Fig. EXPLANATION OF PLATE IX. 



1. Transverse section to show the effect of the mycelium of 



Panus stypticiis upon the wood of alder, "a" shows the 

 more rapid destruction of the spring wood, while " b" 

 shows the destruction of the more persistent autumn 

 wood, both drawings being taken from the same section. 



^ 534- 



a. The destruction of the less lignified fibres is shown in the 



regions "c," " d," and " e," while the medullary rays and 

 more highly lignified elements near "/" are seen to be 

 more persistent, "g" are walls which have been practically 

 consumed except for the middle lamella. Removal of 

 secondary thickening and later of the middle lamella is 

 represented at " h," "i" shows a hypha penetrating 

 through a cell wall, the middle lamella having been dis- 

 solved at the same time as the other part of the cell wall. 

 At"n" secondary thickening and middle lamella have 

 been removed. X 534. 



b. Near "j" can be seen the enlargement of the pits, which 



takes place in the autumn wood cells. At "k" are ele- 

 ments which have lost some of their secondary thickening. 



X 534;, ^^ 



2. "a," "b," "c," "d," and " e" are successive stages in the 



development of the sporophore — ventral views, "a'," 

 " c' ," " d' " and " e' " are lateral views natural size. 



3. Cystidia found at the free margin of the gills, x 534. 



4. a, b, c, longitudinal sections through young fruit bodies. 



5. This figure shows sporophores which have developed upon 



wood fixed horizontally to a chnostat; the pilei of the 

 fruit bodies have expanded vertically. Sporophores are 

 about natural size. 



6. Abnormal sporophores which have developed in a dark 



position in the laboratory. Natural size. 



7. Section through hymenium. X 534. 



a. Basidia and attachment of basidio-spores. Figure also 



shows cystidia. x 534. 



b. Shows a cystidium with a pointed end. x 534. 



