ASCOMYCETES 



241 



generally followed later in the season by the development of peri- 

 thecia, which latter may be differentiated in newly developed 

 stroma, or in the stroma which has borne the Tubercularia stage. A 

 longitudinal section of the perithecia in a related fungus is shown 

 in Fig. 103. The wall of the perithecium consists of an interwoven 

 layer of threads having almost a pseudoparenchymatous appearance. 

 The asci develop from the base and sides, converging toward the 

 apex, each ascus being club-shaped, measuring 60-90 X8-12/1, and 



Fig. 102. Nectria cinnabarina, Section of Sporodochium, 

 with Young Perithecium. (Photograph by E. J. Durand) 



containing eight elliptical spores, which at maturity become two- 

 celled by a partition which may divide the spore into two some- 

 what unequal parts. The spores are about 14-16 x 5-7/x. 



In artificial culture the mycelium develops rapidly, and usually 

 upon almost any of the nutrient media. Upon canes, stems, or 

 other solid media the tuberculiform stroma is readily produced. 

 Both conidia and ascospores germinate readily. In such cultures 

 conidia are produced irregularly upon small branches of the 

 hyphse and sometimes abscised more or less directly from large 



