LIST OF ILLUSTRATIONS 



FIG. 



1. Section through canker ; . . . . . frontispiece 



2. Transverse section of one-year-old stem of larch . . page 8 



3. ,, ,, ,, three-year-old stem of larch . facing page 8 



4. ,, abnormal wood ,, 8 



5. Method of formation of periderm ..... page 10 



6. Longitudinal section of phloem .....,, 11 



7. Transverse section of phloem ,,13 



8. Canker healed on both sides ..... facing page 18 



9. Canker which has nearly girdled stem . . . ' ,, 18 



10. Mycelium of Dasyscypha in wood of larch . . . page 27 



11. Radial longitudinal section of abnormal wood . . ,, 32 



12. Stages in the development of a canker . . . 34 



13. Canker on young larch showing swelling at back . facing page 36 



14. Canker showing swelling at sides ....,, ,,36 



15. Apothecia of Dasyscypha calycina on dead larch stem. 



Dry weather 37 



16. Apothecia of Dasyscypha calycina on dead larch stem. 



Wet weather . ,,37 



17. Section through apothecium of Dasyscypha calycina . . page 38 



18. Dasyscypha calycina, reproductive organ's . . ,, 40 



19. Ascus which has discharged its spores . . . 41 



20. Spores and germination ........ 43 



21. Growth of mycelium in drop cultures . . . 45 



22. Pure culture of Dasyscypha calycina on nutrient 



gelatine facing page 48 



23. Pure culture on sterilized larch stems showing 



apothecium ,,48 



24. Canker showing origin from branch ,,56 



25. Subsequently 



healed on one side ....... ,,56 



26. Cork layer across base of branch page 60 



27. Canker fungus spreading down from a branch . . facing page 61 



28. Spread of fungus down the branches ... ,, , 61 



