EXPULSION OF ASCOSPORES 
Field tests already carried out show that these results are no 
indicator of what may be expected under natural field conditions. 
Summary 
1. Under artificial conditions in the laboratory spore expulsion is 
entirely inhibited at low temperatures. At higher temperatures there 
is a gradual increase in expulsion, with the optimum between 68° 
and 80° F. Spore expulsion was tested at temperatures ranging from 
36° to 100° F. The results obtained in the laboratory substantiate 
the field results which have shown the cessation of spore expulsion 
during the winter period. 
2. Perithecia show an almost phenomenal power of spore produc- 
tion^ as shown by the fact that spores were expelled from some 
specimens every day for 168 days. Some perithecia were still active 
when the test was discontinued. 
3. The necks of the perithecia play an important part in the 
mechanics of spore expulsion. Perithecia from which the necks have 
been removed cease to expel spores. Under favorable conditions for 
growth the necks will be regenerated, and with the formation of new 
necks spore expulsion is resumed. 
4. Expulsion continues from inverted perithecia, the spore prints 
having a characteristic form. The asci are apparently brought to the 
ostiole as a result of pressure within the perithecium. 
5. Spore expulsion will occur in a saturated atmosphere but 
appears to be more pronounced when specimens are permitted to 
dry out gradually. 
6. Direct wetting of the stromata is not necessary for spore expul- 
sion, but sufficient moisture may be absorbed from below. This 
points to the probability that fallen logs or bark bearing perithecial 
pustules may absorb sufficient moisture from the wet ground to cause 
spore expulsion. 
7. In general all of the perithecia of a pustule are not expelling 
spores at the same time. The reverse is sometimes true for small 
pustules, but for larger pustules the maximum number of active 
ostioles varies from 30 to 90 per cent of the total. 
8. Even under laboratory conditions, alternate wetting and drying 
does not inhibit the process of spore expulsion, but the best results 
are obtained from specimens moistened every other day. 
