326 NINETEENTH REPORT. 



EXPLANATION OF PLATES. 



Plate XII. 



The disease in various stages. (Leaves naturally infected). (Photo 

 by G. H. Coons.) 



Plate XIII. 



Fig. 1 — (a-g), showing various shapes of spores; (h), end view of 

 spore, showing scar of attachment. 



Fig. 2 — Knob-like projections on some conidiophores. 

 • Fig. 3 — Secondary tip cell at (b). 



Fig. 4 — Relation of conidiophores to main mycelium. 



Fig. 5 — Spore giving rise directly to conidiophores bearing new spores. 



Fig. 6 — Typical spore and conidiophore. 



Fig. 7 — Typical leaf spot, showing concentric rings. 



Fig. 8 — Clover leaf, showing typical infection. 



Fig. 9 — Young leaf, with infection spreading to petiole (a). 



Fig. 10 — Leaf in last stages of disease, showing the shriveled condi- 

 tion of the leaflets (b, c). Note aggregation of small spots at (a). 



Fig. 11 — Germinating seed, with seed coat completely enveloped by 

 the fungus growth ; also the tip of the radicle attacked by fungus. 



Fig. 12 — Petiole infection, showing linear streaks. 



Fig. 13 — Young mycelium. 



Figs. 11-18 — Old mycelium found in culture. 



Figs. 19-20 — Toruloid mycelium, submerged in culture. 



Figs. 21-29 — Method of spore formation. 



Plate XIV. 



Figs. 1-6 — Spore germination (in clover juice). 



Fig. 7 — Spore giving rise by budding to what appears to be a young 

 spore (a). 



Fig. 8 — Spore germinating in water. 



Fig. 9 — Tip cell of conidiophore germinating after spore has fallen. 



Fig. 10 — Section through leaf (somewhat diagrammatic), showing 

 how the tissue is completely disintegrated and invaded by the fungus. 

 Note fungus spreading into liealthy tissue at edge of spot. 



Fig. 11 — Early stage of infection; mycelium emerging through stoma. 



Plate XV. 



Plants sprayed witli an old attenuated culture. Ten days. (Photo by 

 G. H. Coons.) 



