34 



THE LARCH CANKER 



large intercellular spaces. All the cells in the neighbourhood 

 of the fungus are killed by secretions, and the fungus follows 

 these secretions and feeds on the cells which have been 

 killed by them. The further development of the canker can 

 best be followed by reference to the accompanjdng diagrams. 



ABC 



D 



Fig, 12. — Diagrams showing stages in the dcA'elopment of a canker : 

 A, first spring ; B, first autumn ; c, second spring ; D, third spring ; e, 

 fourth spring. For description, see text. 



Fig. 12, A, shows a transverse section of a three-year- 

 old stem in which a portion ' x ' has been attacked and 

 killed by Dasyscypha. In the spring of the first year the 

 fungus has not reached the cambium, but is near enough to 

 the section ab of the cambium to have affected it and 

 caused it to make the abnormal wood ab of fig. 12, b. 

 This latter figure shows the state of affairs at the end of 



