148 ASCOMYCETES. 



Taphrina. 



The whole mycelium is subcuticular and differentiated into 

 one portion, which remains sterile, and into an ascogenous part. 

 Perennation of the mycelium does not occur. The species pro- 

 duce spots or hypertrophy on leaves or carpels. 



A. The fertile hyphae are completely used up in the for- 

 mation of the asci. 



(1) Asci with a stalk-cell: T. hullata (Berk, and Br.). 



T. ostryae Mass. T. Sadebeckii Joh. T. aure-a 

 (Pers.) (may also occur without a stalk-cell). 



(2) Asci without a stalk-cell : T. filicina Eostr. T. 



polyspora (Sorok.). T. carnea Joh. T. coerulescens 

 (Mont, and Desm.). T. virginica Seym, and Sad. 

 T. extensa (Peck.). 



B. The fertile hyphae are not completely used up ; asci with 

 a stalk-cell : T. betulae (Fuck.). T. ulmi (Fuck.). T. celtis Sad. 



Taphrinopsis. 



Mycelium and hymenium developed only inside the epidermal 

 cells. T. Lanrericia Giesh. 



Magfnusiella. 



The mycelium inhabits the inner tissues of living plants and 

 is always parasitic. Asci ai-e formed at the extremities of 

 branches of the mycelium, either between the epidermal cells 

 or between cells of the inner tissues. The asci contain more 

 than four spores, which generally produce conidia inside the 

 ascus. The species generally cause leaf-spots, more rarely they 

 appear on stems. 



(a) Asci without a stalk-cell : M. potentillae (Farl.). M. lut- 

 escens (Rostr.). M. flava (Farl.). M. githaginis (Eostr.). M. 

 umbelliferarum (Eostr.). 



(6) Asci with a stalk-cell : M. fcisciculata Lag. et Sad. 



Giesenhagen {loc. cit.) comes to the conclusion that the species 

 of the parasitic Exoasceae have developed from a common 

 ancestor simultaneously with the species of the higher plants 

 inhabited by them, and that the development of host and parasite 



