A SERIOUS LETTUCE DISEASE. 
123 
TABLE XI— Continued. 
Age in Days. 
98 
105 
112 
119 
126 
133 
140 
147 
154 
161 
168 
175 
182 
189 
Per Cent of 
Germination. 
90 
75 
75 
50 
75 
50 
25 
10 
1 
0 
0 
0 
0 
0 
Medium 
Used in 
Cultures. 
4% Sugar Solution. 
4% Sugar Solution. 
Lettuce Broth. 
Lettuce Broth. 
Lettuce Broth. 
Lettuce Broth. 
, 
Lettuce Broth. 
Lettuce Broth. 
% 
Lettuce Broth. 
Lettuce Broth. 
Lettuce Broth. 
Lettuce Broth. 
Lettuce Broth. 
Lettuce Broth. 
While there is considerable fluctuation in the results the gradual 
falling off in germinations after the 125th day and the total lack of 
germination after 154 days or about 5 months seems to indicate that 
the ascospores do not live longer than this time. It is to be noted that 
the spores in these instances were kept dry. If they were allowed to 
become moist, as through absorption of water from a humid atmo¬ 
sphere, they immediately germinated. It is thus apparent that their 
only condition of longevity is in a dry state and that the results re¬ 
ported above therefore, represent their maximum life. Under other, 
perhaps under all normal conditions, their life is undoubtedly short. 
In some cases cultures of ascopores in the sugar solution were 
examined after 26 hours. It was found that while at first growth had 
been normal, Fig. 26a, very much distorted hyphse, Fig. 26b, oc¬ 
curred in abundance and that the distorted cells were vacuolate after 
the manner of old hyphse. 
Infection by Ascospores. 
The question of infection conditions is one of highest importance. 
Many tests were made to determine under what conditions ascospores 
could produce infection. The following trials are typical: 
A number of fresh, healthy lettuce leaves was placed in culture 
dishes and inoculated with ascospores in the ways indicated below. 
