190 Infection Experiments with Various Uredinece. 
I add some results on the temperature of germination and on 
the keeping power of spores. 
Spores left for twenty-four hours in a temperature rising slowly 
from O n —7°C shewed no germination. On being placed in a tem¬ 
perature of 20° they germinated freely. 
At 6 n —6'5° about half the sowing germinated at all tempera¬ 
tures from 7"—21°, free germination takes place. 
At 21° rising to 25° all the spores germinated ; but the tubes 
were curled and had wavy edges. 
At 24"—25° never more than one-eighth of the sowinggerminated. 
At 30" no germination takes place and the spores will not 
germinate when removed to a lower temperature. 
Kept dry at 35" for eighteen hours and them removed to a 
temperature of 17°, free germination took place. 
Uredospores of chrysanthemum-rust were kept in a dry test- 
tube in a cool room from March 16th to May 26th, a period of 
seventy-one days. At that date about one quarter of the sowing 
germinated, but a week after none did so. 
Aecidiospores of Phragmidium rosae- alpinae kept in the same 
-conditions from May 20th till August 10th, a period of eighty-two 
days. On that date only one spore in a sowing germinated, but on 
July 28th quite half did so. 
In conclusion I should like to express my gratitude to Professor 
Marshall Ward, at whose suggestion the work was begun and under 
whose supervision it has been carried out, and also to all those who 
have taken the trouble to collect various rusts for me. 
DESCRIPTION OF FIGURES ON PLATES V. and VI., 
Illustrating Miss Gibson’s “ Notes on Infection Experiments 
with Various Uredine^.” 
Fig. 1. Germ-tube of uredospore of U. Geranii entering stoma of C. palustris 
(2nd day). 
Fig. 2. Underside of epidermis of C. palustris shewing substomatal swelling 
of germ-tube of uredospore of P. Menthae (2nd day). 
Fig. 3. Germ-tube of Aecidiospore of Uromyccs Poae entering R. Ficaria 
(2nd day). 
Fig. 4. Stoma, etc., of C. palustris shewing uredospore of U. Geranii germ- 
tube and sub-stomatal swelling emitting hypha (4th day). 
Fig. 5. Under side of epidermisof C. palustris shewing uredospore of U. Poae, 
germ-tube and sub-stomatal swelling emitting hypha (2nd day). 
Fig. 6. Germ-tube of uredospore of U . Geranii entering stoma of C. palustris 
and penetrating deep into mesophyll (4th day). 
Fig. 7. Germ-tube from uredospore of U. Geranii entering stoma of 
C. palustris (2nd day). 
Fig. 8. Germ-tube of uredospore of U. Chrysanthemi entering stoma of 
R Ficaria (3rd day). 
