ILLUSTRATIONS 



Two-year-old cane-field on worn-out land, showing dying out . Frontispiece 



FIG. PAGE 



1. Cross section of leaf . . . . . . .14 



2. Lower surface of leaf showing stomata . . . . .14 



3. Trichomes from leaf . . . . . . .15 



4. Diagram of longitudinal section of young root . . . .15 



5. Cross section of young root . . . . . .15 



6. Seedling plant showing root hairs . . . . .16 



7. Particles of soil held in place by root hairs . . . .16 



8. Root hairs ........ 16 



9. Cross section of dicotyledonous stem . . . . .16 



10. Cross section of monocotyledonous stem . . . .17 



11. Sweet potato affected with wet rot due to Rhizopus nigricans . 22 



12. Rhizopus nigricans, showing sporangia . . . .22 



13. The sporangia of Saprolegnia, showing the formation of zoospores . 24 



14. Conidiophores and conidiospores of Penicillium . . .24 



15. Conidiophores of powdery mildew ..... 25 



16. Sporangium of Rhizopus nigricans . . . . .25 



17. A pycnidium . . . . . . . .25 



18. Zygospore of Rhizopus nigricans ..... 26 



19. Oospore of Albugo Candida ...... 26 



20. A sporocarp of powdery mildew ..... 26 



21. Gall containing Synchiiriutn ...... 33 



22. Pythium Debaryanum, a fungus having aseptate mycelium during its 



vegetative condition ....... 36 



23. Radish affected by white rust, Albugo Candida . . .38 



24. Peronospora Schleideni, a fungus with a much-branched conidiophore 40 



25. Sporophores of late blight of potato, Phytophthora infestans . . 41 



26. The yeast plant, Saccharomyces ..... 42 



27. Peach leaves affected with leaf curl, Exoascus deformans . . 43 



28. Claviceps purpurea, or ergot ...... 45 



29. Wasps (Polistcs (?) lineatur, Fabr) killed by Cordyceps . . 47 



ix 



