128 



Mycologia 



Pfeffer in his Physiology of Plants," 2d. edition, v. 3, pp. 149- 

 150, fig. 34, has described a case of ascospore discharge which 

 resembles the above only in the behavior of the outer wall. Here 

 the inner wall, instead of breaking above the ring formed by the 

 outer wall, breaks at the top, and the spores are discharged not 

 all at once but one by one. First one spore takes its place imme- 

 diately at the apex, the inner wall breaks at that point, and the 

 spore is thrown out. The next spore closes the opening of the 

 inner wall and remains there until the pressure inside of the 

 ascus becomes great enough to cause ejection. After this spore 

 is thrown out, the next one takes its place and so on. 



The method of ascospore discharge described here for some 

 Pyrenophora and Pleospora species is the only method of asco- 

 spore discharge observed by the writer for these fungi. The ma- 

 terial studied was gathered at different times throughout the 

 spring and summer of 1918, and also during the early part of 

 February, 1919, from different localities around Madison, Wis. 



Department of Plant Pathology, 

 University of Wisconsin. 



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