ASCOSPORE EXPULSION OF ENDOTHIA PARASITICA 445 
The fact that perithecial pustules would not exhaust their power 
to expel spores in the course of a single season is even more clearly 
shown by the traps at Martic Forge than by those at West Chester. 
Pustules tested by traps 1-50 must have expelled spores during 1912, 
before the traps were set. All of these traps showed active ostioles 
during 1913, and all but five of them expelled some spores during 
1914. Pustules tested by traps 51-75 probably expelled their first 
spores during the spring and summer of 191 3. All of these showed 
perithecial activity during 1914, most of them expelling spores in 
large numbers. Fig. 5 represents slides taken from traps 52 and 62 
during July, 1914, and shows how copious the expulsion may be 
during the second season. No heavier shooting was obtained from 
any of the traps even during their first season of activity. 
The accompanying chart (Fig. 6) represents the duration of 
expulsion and the seasonal activity for the traps at Martic Forge. 
In some instances the tree was entirely dead and the bark peeling 
off at the time the trap was set, early in 1913. Nearly all of these 
cases showed continued perithecial activity during 191 3, and most 
of them had not entirely lost their power to eject spores in 1914. 
This is best shown by traps 10, 43 and 50 (Fig. 6). 
There is a difference between the continued activity of young and 
mature pustules. The former continue to shoot spores unabated 
throughout the entire season, whereas the maturer pustules eject a 
larger number of spores during the early part of the season and show 
a gradual decline toward the winter months. In Table XI is pre- 
sented the record of expulsion of ascospores for each rain period during 
the active season of 191 3 for typical young and mature pustules. 
Expulsion of Ascospores from Bark Shed from Old 
Infections 
Trap 41 at West Chester was discontinued in April, 1914, the 
bark to which the trap was attached being shed from the tree. In 
order to determine whether perithecia in bark shed from trees would 
continue to expel spores, five representative pieces from bark col- 
lected on the ground beneath trap 41 were brought to the laboratory 
and tested for ascospore expulsion. Each of the pieces (1X3 inches) 
showed active ostioles, the maximum number for any day during the 
progress of the test being forty. This activity was less than from 
similar bark taken directly from cankers. Bark shed from the rail 
