2i8 Exflanation of Plates. 



PLATE XXVIII. 



(All Figures x 500 unless otherwise stated.) 



USTILAGO. 



Fig. 



19. Spores of U. tritici. 



20, 21. Germinating spores of U. tritici, showing typical curved germinal tubes. 

 22, 23. Strong growth from spores of U. tritici after being four days in water. 



24. Spores of U. hromivora. 



25. Germinating spores of U. hromivora after 48 hours in hay infusion. Promycelium 



giving rise to conidia and one extremely long septate tube. 



26. Two germinating spores of XJ. hromivorn, one with conidia forming. 



27. Spore germination of U, hromivora in nutritive solution (after Brefeld) _ x 400 



