502 



Journal of Agricultural Research 



Vol. m. No. 6 



The next two days were fair, and as was expected for these weather con- 

 ditions, no spores of this Endothia were caught. In the evening of August 

 22 there was a rain of 0.25 inch; 6 plates, therefore, were exposed early 

 the next morning before the sun had dried the vegetation. Although 

 the ascospore traps gave evidence that expulsion had occurred, no posi- 

 tive results were obtained, which is explained by the fact that again too 

 long a time had elapsed after the rain ceased. 



Dry, hot weather now continued until the afternoon of August 27, and 

 the exposure plates yielded no evidence of the presence of spores of Endo- 

 thia parasitica in the air. In the afternoon of August 27, however, two 

 thunder storms occurred, in consequence of which the regular routine 

 was departed from. Tables II and III show the outcome of the tests of 

 this date. After the first storm two sets of plates were exposed in the 

 course of an hour and a half. Two out of the second set yielded colonies 

 of E. parasitica. Since the ascospore-trap tests (Tables X and XVII) did 

 not give evidences of expulsion occurring when the first five plates were 

 exposed, negative results were to be expected in those plates, and it is 

 not surprising that only two out of the second set of seven plates yielded 

 colonies of E. parasitica when the 19 ascospore traps examined for this 

 particular period showed evidence of expulsion from only one perithecium. 

 The meagerness of these results is partially accounted for by the small 

 amount of rain, rapid drying, and the fact that the perithecia had hardly 

 been wet a sufficient length of time. 



Table III. — Record of exposure plates made on August sy, IpiJ, at West Chester, Pa. 



BEFORE RAIN. 



RAIN NO. I (0.12 INCH, 3.15 TO 3.28 P. M.) 



48 p. m 



50 p. Ill 



49 p. m 

 48 p. m 



51 p. m 

 10 p 

 12 p 

 14 p 



ISP 

 17 p 

 40 p 

 12 p 



