ASCOSPORE EXPULSION OF ENDOTHIA PARASITICA 447 
Summary 
1. Expulsion of spores from the perithecia of Endothia parasitica 
begins in the spring with the first warm rains, and increases to a 
maximum of activity as conditions become more favorable, to be 
followed by a decline in the fall when lower temperatures prevail, and 
ceases entirely during the cooler portions of the year, although there 
may be an abundant rainfall. During 191 3 the period of expulsion 
extended from about the middle of March to the middle of November. 
For 1912-13 there were 19 rain periods during the fall, winter and spring 
with no expulsion of ascospores, and in 191 3-14 there were 18 rains 
which induced no expulsion of ascospores. During one third to one 
half of the year there is then no expulsion of ascospores, but during 
the remainder there is an abundant expulsion with each rain of any 
consequence (0.10 + ) except in a few instances when the temperature 
drops below the minimum. 
2. Perithecial pustules of the chestnut blight fungus show a re- 
markable power of spore production. This power is not exhausted! 
during the course of a single season, and in many cases is as marked 
during the second season as during the first. Our results point also 
to the conclusion that pustules first producing mature perithecia 
in the fall may continue to be a source of spores during the two follow- 
ing seasons of perithecial activity, the maximum of production occur- 
ring during the season following their maturity, with a gradually dimin- 
ishing production of spores during the next season. This remarkable 
power is due to successive maturity of asci, to successive maturing of 
perithecia, and the successive maturing of stromata throughout the 
season. 
LITERATURE CITED 
1. Rankin, W. H. The Chestnut Canker Disease. Abstract. Phytopathology 2: 
99. 1912. 
2. Rankin, W. H. How Further Research May Increase the Efficiency of the 
Control of the Chestnut Bark Disease. Proc. Pa. Chestnut Bl. Conf. 46-48. 
1912. 
3. Anderson, P. J. and Babcock, D. C. Field Experiments on the Growth and 
Dissemination of the Chestnut Blight Fungus. Bull. Pa. Chestnut Bl. 
Comm. 3: 1-45, pis. 1-15. 1913. 
4. Heald, F. D. Pathological Investigations. Rep. Pa. Chestnut Bl. Comm., 
July I to Dec. 31, 1912: 40-42, figs. 22-38. 1913. 
5. Heald, F. D. and Gardner, M. W. The Relative Prevalence of Pycnospores and 
Ascospores of the Chestnut Blight Fungus During the Winter. Phyto- 
pathology 3: 296-305, pis. 26-28. 1913. 
