ASCOSPORE EXPULSION OF ENDOTHIA PARASITICA 44 1 
the exact period during which ascospores were expelled after each 
rain, still the maximum and minimum temperatures during each rain 
period (Tables VI-X) show that the minimum temperature for 
expulsion in the field corresponded quite closely with that in the 
laboratory. The rain of April 14, 191 3, offers a good example of a 
heavy rain with no expulsion, due to low temperatures (Table VII). 
Although copious expulsion occurred both before and after this 
date, and the precipitation had been heavy (1.15 in.), the temperatures 
were below the minimum for perithecial activity. 
Fig. 4. Diagram showing the relative intensity of ascospore expulsion at 
Martic Forge, Pa., during the season of 1913. 
The number of rains for the entire period covered by our investi- 
gations and the number of rains following which ascospore expulsion 
took place, are shown in Table X. 
The seasonal relation of expulsion at Martic Forge for the year 
1 91 3 was somewhat different from that at West Chester. At the 
latter place the monthly percentage of traps showing expulsion in- 
creased suddenly from March to a maximum in May; during June 
and July there was a decided decrease, but after July there was 
abundant expulsion until November (Fig. 2). At Martic Forge there 
