1900] THE HAUSTORIA OF THE ERYSIPHEZE 183 
33. VON MouL: Die Traubenkrankheiten. Bot. Zeit. 10:9 and 31. 1852. 
" : Bot. Zeit. 1x: 585. 1853. 
35. WARD: Ona lily disease. Ann. of Bot. 2: 319-382. /. 20-24. 1888. 
36. WINTER: Rabenhorst’s Kryptogamen Flora 1? : 22. 
. WISSELINGH: Mikrochemische Untersuchen iiber die Zellwande der 
Fungi. Jahr. f. wiss. Bot. 31 : 619-687. A/. 77, 78. 1898. 
38. ZANARDINI: Gazzetta officiali di Venezia, June 1. 1853. 
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EXPLANATION OF PLATES XI AND XII. 
All the figures were drawn by the aid of the Abbé camera. 
Magnification of figs, 9, 77, 13, 22 to 30, 900 diameters ; figs. 76, 28, 2000 
diameters ; figs. 72, 33, 400 diameters; all other figures, 1800 diameters. 
IGS. I-15. Erysiphe communis on Geranium maculatum. 
Fic. 1. First stage in penetration, marked by spot on inner surface of 
host ect 
IG. 2. Penetrating tube just beginning to make its way through epider- 
mal wall. Wall thickens as tube grows. 
Fic. 3. Having enlarged at a point in line with the inner boundary of the 
es abe wall the tube continues its growth. 
Fig. 4. Further stage in penetration. Cellulose papilla elongates as ~ 
tube ee Distal end of cellulose in growth begins to show signs of disin- 
tegration. Nucleus of host-cell on basal wall of cell. 
IG. 5. Distal end of penetrating tube now begins to enlarge. Cellulose 
further disciganived. The proximal end of rca not disintegrating, but 
destined to remain as collar about neck of haustoriu 
_*IG. 6. Young haustorium escapes from cellulose aaseen and is devel- 
—— — sheath. 
- 7. Stage before entrance of haustorium nucleus. Stretched and 
intruded plasmic membrane of host-cell forms bounding membrane of er 
which in this case is devoid of contents. 
Fig. 8. Haustorium without sheath. 
Fic. 9. Middle haustorium in optical section, the two at end in longi- 
tudinal Sh Sheath present about haustoria. 
Fig. 10. Plasmolyzed cell showing collar as an ingrowth of coke 
Partly in perspective. 
G. 11. Haustorium with two nuclei. Septum also found across neck. 
G. 12. Haustorium without sheath. Protoplasm of host- sessional 
Sides of neck, 
Fic. 13. Haustorium shows septum across neck. 
Fig. 14, Elongated nucleus in mycelial hypha. 
15. Membrane absent from sheath, which here consists of lumps of 
pS eee ee — adhering to body of haustorium. 
