LABOULBENIALES 367 



of its lateral walls. These rupture the outer wall at the base of the 

 primary appendage. The cavity continues to grow until the perithecia 

 form from the base of the circle of secondary appendages. The anther- 

 idial appendages (Fig. 247, 7) usually consist of three superposed short 

 cells bearing at the tips one to three large, bacilliform spermatia, which 

 soon fall off and are sought by the trichogynes. Although the perithecia 

 arise endogenously, their development is normal (Fig. 247, 8). 



Fig. 246. — Zodiomyces vorticellarius. Mature individual. (X 195; after Thaxter, 1896.) 



Laboulbeniaceae. — The central family which has given the order its 

 name is the largest in the order with about thirty genera, parasitic on 

 most of the groups of insects. The ontogeny has been more fully studied 

 and will be given in detail. 



The ascospores are formed in asci, occasionally eight, usually four 

 by the degeneration of four nuclei (Fig. 252, 7 and 8). Very early they 

 are unicellular, later except in Amorphomyces dividing into a long basal 

 and short apical cell (Fig. 252, 9). They are oriented in the ascus accord- 

 ing to their later bipolar development, with the basal cell uppermost 

 and are surrounded by a gelatinous, sticky sheath, which is usually 



