Specialization of Parasitism in the Erysiphaceae. i 17 
198b. October 4. No signs of infection until this date, when 
one inoculated leaf bore a little group of five conidiophores ; con¬ 
trols free. 
88b. August 20. On one inoculated leaf four little tufts of 
conidiophores, 8-15 in each ; controls free. August 26. Conidio¬ 
phores nearly died away,—no signs of any infection elsewhere. 
September 3. Fungus quite died away. October 7. No trace of 
any fungus on any leaves. 
TABLE IV. 
Infection-Experiments with conidia of E. Graminis on 
Dnctylis glonierata. 
lixper. 
No. 
Date. 
1903 . 
Species used as Host. 
No. of 
leavesino- 
culated. 
No. of 
leaves 
infected. 
66a 
July 27 
Dnctylis glomcrata 
3 
-- 
3 
66 b 
„ 27 
• • • )) • • • 
3 
3 
73a 
Aug. 1 
... 99 ... 
3 
2 
78a 
„ 4 
... n • • • 
3 
3 
66 c. 
July 27 
Avena sativa 
3 
0 
73d 
Aug. 1 
... 99 ... 
3 
0 
66d 
July 27 
Sc cal e cerealc 
3 
0 
66 e 
„ 27 
Triticum vulgare 
3 
0 
73b 
Aug. 1 
Lolium temulentum 
3 
0 
73c 
,, 1 
Hordeum vulgare 
3 
0 
78b 
„ 4 
Agropyron repens 
3 
0 
Remarks. 
66a. August 4. The three inoculated leaves with numerous 
powdery patches of Oidium ; controls (30) all free. August 7. The 
three infected leaves each with numerous very powdery snow-white 
Oidium- patches ; controls still free. August 11. Fungus beginning 
to spread to controls. 
66b. August 4. The three inoculated leaves all infected, and 
bearing more or less powdery Oidium- patches; controls (33) all 
free. August 7. The three inoculated leaves with densely powdery 
snow-white Oidium- patches ; controls still free. August 11. 
Fungus spread to several controls. 
73a. August 5. A few flecks of mycelium on the three 
inoculated leaves. August 8. One leaf virulently infected and 
bearing numerous almost powdery Oidium- patches ; a few patches 
of Oidium on the second leaf; third leaf not infected. August 11. 
The two leaves densely covered with very powdery Oidium- 
patches,—the third leaf missed infection ; controls still free. 
August 25. Fungus spread over all the plants in pot. 
78a. August 11. Well-grown powdery Ozrfww-patches on all 
the three inoculated leaves; controls free. August 20. Oidium- 
patchcs very powdery on all the inoculated leaves, and beginning 
to spread to controls. 
