Mar. as. 1915 Disseifiination of Chestnut-Blight Fungus 



507 



Table VI. — Record of exposure plaUs made on September 21, IQ13, at West Chester, 



Pa . — Continued 



RAIN NO. 3 (.\BOUT 0.03 INCH, I.4J TO 2. II P. M.) 



5086 



5087 



2.53 p.m. 

 3.10 p.m. 



o 

 20 



RAIN NO. s (ABOUT 0.03 INCH, 3.26 TO 4.07 P. M.) 



5086A 



S087A 



5088 



5089 



SO9O 



509 1 



4.08 p. m 

 4.17 p. m 

 4-35 P- m 

 4-SSP- m 

 5.16 p. m 



5-33 P- m 



In the afternoon of the same day three light showers occurred, and 

 one plate exposed in the interval after the second of these caught 20 

 ascospores. After the first of these showers the exposure was cut too 

 short by the recurrence of rain to give a reliable test. It will be seen 

 that none of the six plates exposed during the i hour and 36 minutes 

 after the last shower yielded colonies of Endothia parasitica, despite the 

 fact that 6 out of 1 1 ascospore traps examined (Tables XIV and XVII) 

 gave evidence that expulsion had occurred during that period. In 

 explanation it may be stated that the wind had attained a higher 

 velocity at this time and was blowing quite briskly in the open. It is 

 readily conceivable that with such a wind the spores as they were ex- 

 pelled might have been transported with such speed and their numbers 

 dissipated so rapidly that none chanced to fall on the rather small area 

 represented by the exposure plates. 



A rather heavy rainfall was recorded on the night of September 21, 

 but it ceased before 12.45 3- ™- Examination of the ascospore traps 

 showed that there was abundant spore expulsion during the night, and 

 5 out of 21 traps gave evidences of the occurrence of expulsion after 

 7.30 a. m., on September 22 (Tables XV and XVII). Of the 13 plates 

 exposed between 5.56 a. m. and 7.35 a. m. but 2 yielded positive results 

 (Table II). No spores were caught in any of the plates exposed there- 

 after, even though two ascospore traps bore evidences of the occurrence 

 of light expulsion after 1 1 .24 a. m. The meager results obtained on this 

 date are no doubt due to the long period of time intervening since the 

 cessation of rain the night before. 



Clear, hot weather prevailed during September 22 and 23, and no 

 spores were caught. 



