THE PARASITIC EXOASCEAE. 147 



According to Sadebeck, the Exoasceas may be divided as 

 follows : 



Exoascus. 



The mycelium perennates in the tissues of twig or bud. The 

 subcuticular mycelium is developed from the perennating one, and 

 becomes completely divided up, without any differentiation, into 

 ascogenous pieces. The species are all parasites and produce 

 hypertrophy of leaves, flowers, and shoots. 



A. The mycelium perennates in the inner tissues of the 

 shoot. Thence, in the next vegetative period, it sends branches 

 into the leaves in process of development, at first into the 

 inner tissues, but later subcuticular for the formation of re- 

 productive parts of the fungus. 



(1) Asci developed in the carpels, which in . consequence 

 become hypertrophied ; asci with a stalk-cell : E. pruni 

 Puck. E. Rostrupianus Sad. E. communis Sad. E. 

 Farlowii Sad. E. rhizipes Atk. E. longipes Atk. E. 

 confiisus Atk. E. cecidomopMlvs Atk. 



(2) Asci developed only in the foliage leaves. 



{a) Asci with stalk-cell : E. insititiae Sad. E. cerasi 

 (Fuck.). E. nanus (Job.). E. deformans (Berk.) E. 

 decipiens Atk. E. acerinus Eliass. 



(6) Asci without stalk-cell : E. purpurascens (Ell. and 

 Ever.). E. aesculi (Ell. and Ever.). 



(3) Asci developed on leaves and fruits. 



{a) Asci with stalk-cell : E. miraMlis Atk. 



B. The mycelium perennates in the buds of host-plants 

 and issues thence in the next vegetative period to develop in 

 young leaves, subcuticular only. 



(1) Asci only on the foliage leaves. 



{a) Asci with a stalk-cell : E. crataegi (Fuck.). E. minor 

 Sad. E. Tosgidnetii (West.) E. epiphyllus Sad. E. 

 turgidus Sad. E. betulimis (Eostr.). E. alpinus (Job.). 



(&) Asci without a stalk-cell : E. carpini Eostr. E. hacieri- 

 ospermus (Job.). E. Kruchii Vuill. 



(2) Asci on carpels ; without stalk-cell : E. alni incanae 

 Kiihn. E. Johansonii Sad. E. rhizophorus (Job.). 



(3) Mycelium grows intercellularly. E. cornu cervi Giesh. 



