184 BOTANICAL GAZETTE [MARCH 
Figs. 16-17. Erysiphe Cichoracearum on Eupatorium perfoliatum. 
Fig. 16. Basal cell of hair containing haustoria. 
Fig. 17. Shows unstained area about point of penetration. Remainder of 
host wall staining darkly. 
FiGs. 19-21. Erysiphe graminis on Poa. Three branching haustoria. 
FIGs, 22-26. Uncinula Salicis on Salix discolor. 
Fic, 22. Epidermal cell containing one haustorium, while from the same 
appressorium another penetrating tube passes through the epidermal cell 
into the subepidermal cell. The sheaths are not visible. 
FIGs. 23-26. Various forms of appressoria giving rise to two or more 
haustoria. 
Fic. 27. Modified haustorium arising from appressorium and penetrating 
mesophyll cell. Host-cell shows exudations on its exterior. A second appres- 
sorium also shown. 
FiG, 28-33. Phyllactinia suffulta ; figs. 28,31 on Fraxinus pubescens ; fig. 
30 on Cornus sp.; figs. 27, 29, 32, 33 on Xanthoxylum Americanum. 
Fig, 28. Part of an intercellular hypha. Guard cells drawn apart and 
hypha not compressed, as in SigZs. 32, 33 
FiG. 29. Smaller haustorium, and arising from end of hypha. Exudation 
on cell of leaf shown, 
Fic. 30. Intercellular hypha consisting of four cells. Haustorium arising 
from side of distal cell. Host-cell below palisade cells. 
Fic. 31. Haustorium arising from end of intercellular hypha and pene- 
trating parenchyma cell connected with bundle. Haustorium contains a 
crystal. 
FiG. 32. Stoma containing initial cells of two intercellular hyphae, one a 
side branch. Origin of the other is indeterminate. 
Fic. 33. Intercellular hypha, with haustorium in cell joining bundle to pali- 
sade cell. Middle cell of hypha is short and thick, and lies on cells of host. 
