Fig. 76. Formation of perithecia by Ceratostomella fivibriata and C. vtonili- 

 jormis. A to N . C. iiiomlijormis. A to H. Initiation of perithecia from 

 primordium consisting of an antheridium and an ascogonium. /. Uninucle- 

 ate protoplasts of antheridium and oogonium before plasmogamy. / to N. 

 Binucleate cells or ascogonial cells within young perithecia. O to U. 

 C. -fivibriata. O. Somewhat later development of perithecium, showing beak 

 formation, and arrangement of ascogenous cells within the perithecial 

 cavity. P. Nuclear fusion to make the primary ascus nucleus, 0- ^' Binu- 

 cleate ascus. S. Quadrinucleate ascus. T. Early and late stages in forma- 

 tion of eight ascospores. U. Habit sketch of mature perithecium. (Andrus 



and Harter.) 



206 



