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MANUAL OF POISONOUS PLANTS 



Fig. 92. Powdery Mildew. Sphaerotheca Casiagnei. 1. Oogonium (o) and anther- 

 idium (a). 2. Separation of antheridium cell. 3. Fertilization and formation of addi- 

 tional cells. 5-8. Further development of cells. All greatly magnified. After Harper. 



Fig. 93. Powdery Mildew of Grass {Erysiplie graminis). 

 A. Oidium stage and mycelium m. B. Perithecium with 

 appendages and mycelium tu. C. Perithecium with asci 

 and ascospores. After Frank. 



