242 



CLASS ASCOMYCETBAE 



J 



Fig. 86. Taphrinales, Family Taphrinaceae. Taphrina deformans (Berk.) Tul. 

 (A) Portion of a leaf section showing asci in various degrees of development. (B) 

 Mature ascus showing empty basal portion. (C) Portion of ascus showing two asco- 

 spores beginning to bud. (D) Subcuticular ascogenous cells seen from above. (E) In- 

 fection of leaf by dicaryon mycelium. (A-D, courtesy, Pierce: U.S. Dep. Agr. Vegetable 

 Physiol. Path. Bull., 20:1-204. E, courtesy, Fitzpatrick: Sci. Agr., 14(6):305-326.) 



into the thin-walled upper portion undergoing further divisions there. 

 The diploid nucleus undergoes meiotic and mitotic divisions, the spindle 

 of the first division being transverse according to Juel (1921). Around 

 the eight nuclei thus formed the ascospores develop. In many species 

 each ascospore undergoes budding so that the ascus becomes polysporous. 

 Miss Wieben's germination experiments showed that four of the asco- 

 spores (and the spores produced from them by budding) are of one sexual 

 phase and four of the other. From Fitzpatrick's studies it is apparent 

 that in T. deformans this distinction does not occur or is not well marked. 

 Lohwag (1934) advances reasons for believing that Taphrina is not 

 a true Ascomycete but a Basidiomycete which has reverted to the ances- 

 tral condition. The normal basidium, in his viewpoint, represents an 

 ascus in which the ascospores have pushed out into projections of the 

 ascus wall so as to become apparently external, although really retained 

 within the wall. In Taphrina the transverse position of the nuclear 

 spindle, the habit of budding on the part of the ascospores, and the pari- 



