Specialization of Parasitism in the Erysiphaceae 115 
August 20. The little group of conidiophores still visible on the 
one leaf; no trace of a fungus on any other leaves. September 12. 
The few conidiophores still persisting, but fungus not increasing 
and not spreading to other leaves. 
76b. “ Subinfection ” only. August 7. A few scattered 
conidiophores, three to ten in number, visible on one leaf; controls 
free. August 20. Fungus died away on the one leaf; no trace of 
any fungus on the other inoculated leaves nor on the controls. 
September 12. Leaves of most of the plants infested with Aphides ; 
a few small powdery Oidium- patches on a few leaves. 
TABLE II. 
Infection-experiments with conidia of E. Gvaminis on 
Agropyron repens. 
Kxper. 
No. 
Date. 
1903 . 
Species used as Host. 
No. of 
leaves ino¬ 
culated. 
No. of 
leaves 
infected. 
65a 
July 25 
Agropyron repens 
3 
3 
65e 
„ 27 
* • • M • • • 
3 
3 
65b 
„ 25 
A. glaucum var. 
3 
0 
65c 
„ 25 
A. acutum. 
3 
0 
65 d 
„ 25 
A. tenerum 
3 
3 
65f 
„ 27 
A. caninum 
1 
1 
Remarks. 
65a. July 31. A few flecks of mycelium with two or three 
young conidiophores on two of the inoculated leaves. August 2. 
Well-grown powdery O/rfbo/i-patches on two leaves, flecks of 
mycelium with young conidiophores on the third; controls all free. 
August 5. The three inoculated leaves all virulently infected with 
numerous powdery OL/non-patches; one control plant (of thirteen) 
now with several flecks of mycelium. August 13. The three 
inoculated leaves beginning to die; fungus spread to several of the 
controls. 
65e. August 3. Flecks of mycelium on the three inoculated 
leaves. August 5. The three leaves virulently infected with 
numerous powdery Oidium- patches ; controls all free. August 7. 
The fungus spread to one control. August 13. The three inocu¬ 
lated leaves beginning to die; fungus spread to several of the 
controls. 
65c. No infection of the three inoculated leaves, but on 
August 13 one leaf of one control-plant bore on the under surface 
a large well-grown powdery Oidium- patch. 
65d. Aug. 5. On one inoculated leaf two isolated groups of 
about ten conidiophores; controls free. August 7. Scattered 
conidiophores on another inoculated leaf. August 13. Weak 
infection—slightly more than “ subinfection ”—of all three leaves ; 
controls all free. September 25. Plants kept in laboratory until 
this date; a few weak patches of mycelium with a few conidiophores 
on two of the younger leaves. 
