TR A METES RADICIPERDA. 



'53 



and the filaments are dissolving and feeding upon the 

 latter (Fig. 14). In the next stage of the advancing 



FIG. 14. Sectional view of a tracheide of the spruce-fir, attacked by the hyphae (a, $) 

 of a Trametes, highly magnified (after Hartig). The upper part of the tracheide 

 has its walls still sound, though already pierced by the hyphae ; the lower part (c) 

 has the walls completely delignified, and converted into cellulose, which swefls up 

 and dissolves. The middle-lamella is also undergoing dissolution. The holes in 

 the walls have been bored by hyphae. 



destruction of the timber the black dots mostly dis- 

 appear, and the white areas get larger ; the middle- 



