Mar. 25, r925 Dissemination of Chestnut-Blight Fungus 507 
a 
TaBLE VI.—Record of exposure plates made on September 21, 1913, at West Chester, 
Pa.—Continued 
RAIN NO. 3 (ABOUT 0.03 INCH, 1.43 TO 2.15 P. M.) 
Wind. 
Plate Time. Length of| Station poe coty Total Se ef 
No. exposure.| No. i and number othia 
Direction. ie yeasts. of fungi. parasitica. 
Minutes. 
5085 | 2.20p.m..... 3% 13 Ss. 6.2 8 160 ° 
RAIN NO. 4 (ABOUT 0,04 INCH, 2.20 TO 2.50 P. M.) 
5086 | 2.53 p.m..... 1534 13 Ss. 6.2 ° 144 ° 
5087 | 3.10p.m.....) 14% 12 Ss. 6.2 ° 35 20 
RAIN NO. 5 (ABOUT 0.03 INCH, 3.26 TO 4.07 P. M.) 
5086A| 4.08 p.m..... 1934 13 Ss. 8.0 Io 58 ° 
5087A] 4.17 p.m..... 14 37 S$. “8.0 3 50 ° 
5088 | 4.35 p.m.....} Io II S. 8.0 4 45 ° 
5089 | 4.55 p-m..... 15 12 Ss. 8.0 6 42 ° 
5090 | 5.16p.m..... 17% II Ss. 8.0 3 38 ° 
5091 | 5.33 p-m..... II Be) Ss. 8.0 5 20 ° 
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 1 hour and 36 minutes 
after the last shower yielded colonies of Endothia parasitica, despite the 
fact that 6 out of 11 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 a. m. 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 11.24 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. 
