Feb. 12, 1917 
239 
Studies of the Genus Phytophthora 
KIND OF SPORE' FORMS PRODUCED AND TIME OF APPEARANCE 
Microscopic examinations from time to time of cultures made in test 
tubes on hard potato agar, oat agar, Lima-bean agar, corn-meal agar, 
and bean pods, and grown at room temperatures, showed that even 
when grown under as nearly identical conditions as possible the different 
cultures did not produce the same spore forms. 
As will be seen in Table I, which shows the spore forms found at the 
end of two and six weeks, certain of the media are more favorable for 
the production of all the spore forms than others, and oat agar is the 
most suitable, especially as regards the sexual bodies. It should be 
borne in mind that the production of the spore forms on the various 
media shown in the table is not absolute, but what may be expected 
under normal conditions. This table was compiled as the result of ob¬ 
servations during the past three years. 
