LIST OF ILLUSTRATIONS 



8 

 8 

 8 

 10 

 11 

 13 

 18 

 18 

 27 

 32 

 34 

 36 

 36 



37 



FIG. 



1. Section tlirough canker ..... frontispiece 



2. Transverse section of one-year-old stem of larch . . 2^(7^ 



3. „ „ „ three-year-old stem of larch . facing page 



4. ,, ,, „ abnormal wood 



5. Method of formation of periderm ..... page 



6. Longitudinal section of phloem 



7. Transverse section of pliloem 



8. Canker healed on both sides ..... facing page 



9. Canker wliich has nearlj- girdled stem 



10. Mycelium of Dasyscypha in wood of larch . . . page 



11. Radial longitudinal section of abnormal wood 



12. Stages in the development of a canker 



13. Canker on yoimg larch showing swelling at back . facing page 



14. Canker showing swelling at sides 

 lo. Apothecia of Dasyscypha calycina on dead larch stem. 



Dry weather . . . 



16. Apothecia of Dasyscyplm calycina on dead larch stem 



Wet weather ...... 



17. Section through apothecium of Dasyscypha calycina 



18. Dasyscypha calycina, reproductive organs 



19. Ascus which has discharged its spores 



20. Spores and germination ..... 



21. Growth of mycelium in drop cultures 



22. Pure culture of Dasyscyplm calycina on nutrient 



gelatine ..... 



23. Pure culture on sterilized larch stems showing 



apothecium ...... 



24. Canker showing origin from branch 



25. ,, ,, „ ,, Subsequently 

 healed on one side ..... 



26. Cork layer across base of branch 



27. Canker fungus spreading down from a branch . 



28. Spread of fungus down the branches 



