CRONARTICM. 



383 



and curl up. 

 unknown. 



In some districts very common. Aecidial stage 



Gymnosporangium.^ 



Teleutospores bicellular and furnished with stalks which have 

 gelatinous walls, so that the spores come to form part of a 

 gelatinous mass.^ The first-formed teleutospores are thick - 



Fig. 21G. — Gymnosporangiuvi clavaiiaeformc. 1, S, 3, Stages in dbvelopment of 

 the spore-cushions. U, 5, 6, Isolated spores (enlarged); 5 is thin-coated, the 

 others are thick-coated. 7, Germinating spore with proniycelium abjointing 

 sporidia (S). d, A germinating sporidium. (After Tubeuf.) 



walled, the succeeding ones are thin-walled. Uredospores do 

 not occur. The aecidia have a thick peridium. The teleuto- 



^v. Tubeuf: (1) Oentralblatt /. Balcter. u. Parasitenkunde, 1891; with a review 

 of the current Literature. (2) " Inf eotionen mit Gymnosporangium. " Forstlich- 

 natunoiss. Zeitschri/t, 1893, p. 75. Woernle, " Anatomisohe Untersuchiingen d. 

 durch Gymnosporangium-Arten hervorgerufenen Missbildungen," idem., 1894. 

 American Literature, see p. 401. 



2. The gelatinous substance is obviously well-adapted to absorb raln-w^ater 

 and so facilitate germination of the teleutospores in situ ; the sporidia pro- 

 duced are then carried off by rain or liberated after the cushions dry again. 



