210 



THE ASCOMYCETES 



ascofronium consists of a basal ascoo^onial cell and a terminal 

 trichogynal portion that projects to the exterior. Whether the 

 spermatia function in fertilization has not been determined, but 

 indirect evidence indicates that they are necessary. For example, 



Fig. 79. Development of Mycosphaerella bolleana. A. Conidiophore fas- 

 cicle of Cercospora bolleana. B. Variation in shape and septation of 

 conidia. C. Young spermogonium just beginning to form spermatia. The 

 stroma is still a loose tangle of hvphae without an outer wall of thick- 

 walled cells. D. Young carpogonial locule with coiled ascogonium devel- 

 oping coincidentallv with the spermogonium. Conidia of the Cercospora 

 stage may be formed on both kinds of young stromata. E. Portion of base 

 of mature carpogonial stroma with ascogenous hyphae and asci borne on 



ascogonium. (After Higgins.) 



the spermatia collect in a film or droplet at the spermogonial ori- 

 fice, and, unless moisture is present to make possible their trans- 

 fer to the archicarpic locules, perithecia are not produced. 

 Furthermore, if material bearing the conidial stage is collected 

 and kept indoors to dry for a month or more before being placed 

 outdoors to hibernate, in most instances the perithecial stage will 

 not develop, because of the lack of moisture in the form of dew 

 or rain at the critical stage when spermatization should have been 



