2G Robert S. Kikby 



same year. In September the germination increased to about 25 per 



cent, and the maximum (50 per cent) was reached during October, 

 November, and December. The percentage of germination fell off 

 gradually during January, February, and March. The latest germination 

 to be observed was in March and April, after which all the ascospores 

 failed to germinate. Thus it appears that most of the ascospores come to 

 maturity and are discharged soon after the winter wheat is planted in 

 the autumn, at which time inoculation and infection usually occur. 



The manner of ascospore discharge from the perithecium has been 

 studied by Hori (1901), McAlpine (1904), and Waters (1920 a). These 

 investigators all agree that the ascospores escape through the ostiole 

 but that they are not shot forth into the air. McAlpine stated further 

 that the asci are expelled one after another, and the ascospores are then 

 set free in the presence of moisture. Waters (1920 a) pictures perithecia 

 which have pushed out coils of mucilaginous matter carrying the asci 

 through the neck with it. He states that this takes place in slightly moist 

 air, that in very moist air a globose mass is formed at the ostiole, and that' 

 in water the moisture dissolves the mucilage and liberates the spores as 

 the asci emerge from the ostiole. A dry mass of asci and ascospores has 

 several times been observed by the writer to have formed at the ostiole, 

 where it remained for several months if there was no rain to dissolve it. 

 Apparently asci and ascospores are discharged only when there is sufficient 

 moisture present to soak up the contents of the perithecium. Perithecia 

 formed in pure culture have not been observed to liberate their spores 

 until placed in water. Field observations seem to indicate that asci 

 and ascospores are discharged during rainy periods, and that usually the 

 splashing rain removes them before they can accumulate at the ostiole. 



The date at which ascospores are mature and ready to be discharged 

 may be determined by immersing perithecia from time to time in water, 

 when, if mature, the ascospores will be exuded. Hori (1901) states 

 that in Japan at least some spores are discharged within ten days after 

 the crop is cut, or about June 23, and Waters (1920 a) states that in 

 New Zealand perithecia put forth tendrils of spores in January (corre- 

 sponding to July in New York). From observations made by the writer, 

 it seems that the date of discharge is greatly influenced by the time of 

 formation of the perithecia and the subsequent moisture conditions. 

 Perithecia have developed as early as June 4 and have been observed 

 discharging their ascospores within two weeks after their formation. 

 It has been noted that perithecia seldom discharge all their ascospores, 

 but retain a certain number which finally disintegrate during April and 

 May following their formation. Ascospore discharge may begin as 

 early as the latter part of June, but it probably does not reach its maximum 

 until September and November, ceasing some time in March or April 

 of the following spring. 



