42 BOTANICAL GAZETTE [JULY 
That without moisture of this sort no infection can take place, 
regardless of all other conditions. 
That the effects of atmospheric dryness are not limited to the 
spore-germination, but produce the following effects upon spore 
production in cases of previous infection: Aecidial dev elopment is 
checked, no “cluster cups” appear, and the mycelium remains dor- 
mant for some time; if moisture conditions occur, spores are at once 
Fic. 21.—Showing same as fig. 20. Milpitas, August 20, 1903. 
ment is similarly checked and changes to a production of teleuto- 
spores in the sori already formed, without regard to season or condi-/ 
tion of the host; with moisture uredospore formation begins again. 
produced, otherwise the mycelium finally dies out. Uredo develop- | 
at once. 
That the teleuto stage is a provision for surviving any condition. 
unfavorable to the fungus, whether of food supply, moisture, tem- 
perature, or resistance by the host, without regard to season. 
That extremes of atmospheric moisture conditions are insufficient 
in most sections of the country to bring out or make effective this - 
direct relation. 
