266 Ward — On Relations between Host and Parasite 
TABLE VII. 
Exp. No. 737. Results showing the comparative germination 
of spores of different ages. 
No. 
Date 
sown. 
Origin of 
spores. 
Age of 
leaf. 
State of leaves. 
State of spores 
sown. 
Temp. 
737 a 
June 27 
R. mollis (1) 
Young 
II 
Fresh 
Naturally shed 
24°-2 5 0 C 
,, of 
>3 
3, (2) 
II 
Scraped off after 
the shedding 
II 
„ b 
>3 
,3 (3) 
Old 
Kept 24 hours 
in moist box 
Naturally shed 
II 
„ v 
II 
33 (4) 
Young 
II 
II 
II 
„ V' 
1 ? 
,3 (5) 
Old 
II 
Scraped after 
shedding 
II 
„ V" 
II 
,3 (6) 
Young 
II 
II 
II 
II 
B. sterilis (7) 
II 
Fresh 
Naturally shed 
II 
„ * 
II 
3, (8) 
II 
II 
Scraped after 
shedding 
II 
„ c" 
II 
,3 ( 9 ). 
Old 
II 
II 
II 
(1) Germinated vigorously in 3 hours. 
(2) None germinated even in 24 hours. 
(8) Only one or two germinated. Several other fungus spores were present. 
(4) Germinated vigorously in 3 hours. 
(5) None germinated, even in 24 hours. Many spores of other fungi present. 
(6) None germinated, though the spores appeared clean. 
(7) Vigorous germination in 3 hours. 
(8) Also germinated fairly well. (9) None germinated. 
spores in certain cases might be due to the presence of the 
spores of other fungi, e.g., moulds, Dematium , &c., while 
something may no doubt be put down to their agency in 
robbing the hanging drops of oxygen, and interfering in other 
ways with the well-being of the Uredospores ; I obtained 
plenty of evidence showing that this is but a minor event 
in cases where the latter spores are capable of rapid germi- 
nation : they can hold their own very well in the race for 
some hours at least, and on green leaves in the open are not 
likely to be injured by competing saprophytes. 
The following Table (VIII) shows the result of a few 
experiments typical of several others made to test the action 
of light. Though the number of trials is as yet too few to 
base any very wide generalization on, the positive results are 
useful, and clearly point to the conclusion that no ordinary 
light affects the germination very seriously ; and even in the 
