214 



THE ASCOMYCETES 



which invests the entire mass of Hberated spermatia. This matrix 

 swells in the presence of moisture, and as a result the spermatia 

 are forced to the exterior of the spermogonium. Their germina- 



FiG. 81. Mycosphaerella cercidicola. A and B. Fascicles of conidiophores, 

 the conidiophores tending to be coremioid. C. Germinating conidiophore. 

 D. Germinating conidia. E. Vertical section of mature spermogonium. 

 F. Vertical section of perithecial primordium with single archicarp. G. 

 Ascus after elongation by rupture of outer ascal membrane. H. Mature 



ascospores. 7. Germinating ascospores. 



tion has not been observed. Each spermatium contains a single 

 nucleus, so large that it practically fills the cell. These charac- 

 teristics are interpreted to indicate that spermatia are male cells. 

 Giiignardia. The best-known species of Guignardia is G. bid- 

 ivelliiy causing black rot of grapes, endemic to North America 

 and introduced into Europe about 1885. It was first described 



