Foie Evans. — The Cereal Rusts. 465 
Fig. 2. Longitudinal section through stoma of wheat leaf, showing appressorium, substomatal 
vesicle, and infecting hypha of P. graminis. Four-day culture. 
Fig. 3. Similar section of wheat leaf, showing substomatal vesicle and infecting hypha with 
haustoria. Four-day culture. 
Fig. 4. Transverse section of wheat leaf, passing through a stoma, in which the appressorium 
and substoma talj vesicle are seen, with the tip of an infecting hypha in the stomatal cavity. P'our- 
day culture. 
Fig. 5. Portion of hyphal filament with young haustorium. 
Fig. 6. Typical haustoria found in the epidermal cells. Four-day culture. 
P. Ph lei-pratensis . 
Fig. 7. Longitudinal section through stoma of leaf of Phleum pratense , showing stomatal 
vesicle and infecting hypha. From an eight-day culture. 
Figs. 8, 9, and io. Typical young haustoria of P. Ph lei-pratensis . 
Fig. 11. Older haustorium, its behaviour towards the nucleus of the chlorophyll-containing cell 
is very characteristic. 
Fig. 12. Two vegetative nuclei in the process of direct division. 
All the figures of uredo infection of P. glumarum on Wheat. 
Fig. 13. Longitudinal section of leaf. Two spores are seen germinating at one stoma. From 
one the germ tube and appressorium are seen, with just a graze of the substomatal vesicle. 
Fig. 14. The next section to the above showing the substomatal vesicle with its first infecting 
hypha, which has formed a haustorium in the first cell with which it has come in contact. From 
a five-day culture. 
Fig. 15. Longitudinal section showing the oval substomatal vesicle just under a stoma, with the 
first infecting hypha, which has become septate at the tip previous to the formation of a haustorium. 
In connexion with some of the nuclei of the hypha, centrosomes are clearly seen. Third-day 
culture. 
PLATE XLI. 
Fig. 16. Transverse section across a stoma, showing the substomatal vesicle in section. Eight- 
day culture. 
Fig. 17. Typical hyphae with their numerous nuclei. Eight-day culture. 
Fig. 18. Large branched haustorium. The host cell nucleus, where the haustorium is almost in 
contact with it, is just beginning to show signs of a fragmentation. Eleven-day culture. 
Fig. 19. Branched haustorium affecting host cell nucleus. The chlorophyll corpuscles are seen 
to have become rounded and swollen, in the act of breaking down. Eleven-day culture. 
Figs. 20 and 21 show how narrow the hyphae may become in the intercellular spaces before 
spore formation. At the tip of the hypha in Fig. 21a nucleus is just dividing. Both from a ten- 
day culture. 
Fig. 22. Portion of a runner, the protoplasm has become much less dense and is very vacuolated. 
The nuclei are in a resting condition, and have distinct nuclear membranes. 
Figs. 23 and 24. Common forms of haustoria. 
Figs. 25-7, 33 and 34. Uredo infection of P. dispersa on Rye. 
Figs. 28-30. Uredo infection of P. triticina on Wheat. 
Figs. 31 and 32. Uredo infection of P. Symphyti-Bromorum on Bromus. 
Fig. 25. Oblique longitudinal section of a stoma of a Rye leaf, showing a portion of a germ tube 
with its appressorium of P. dispersa just over the stomatal slit. 
Fig. 26. Longitudinal section of a five-day culture of P. dispersa on Rye, showing the remains 
of the appressorium, the substomatal vesicle with its two infecting hyphae. 
Fig. 27. Similar preparation to the above. In both cases the sub-stomatal vesicle has become 
divided by a transverse septum. Small centrosomes are seen in connexion with some of the nuclei. 
Figs. 28 and 29. Longitudinal sections of Wheat leaf showing infection phenomena in 
P. triticina. 
PLATE XLII. 
Fig. 30. Transverse section across a stoma showing appressorium, substomatal vesicle, and 
infecting hypha with its haustorium of P. triticina. 
