PLATE 56 

 Cronartium ribicola: 



A. — A drawing of the cell relations near the edge of an secimn to illustrate the forma- 

 tion of the multilayered secial peridium. a, A young aeciospore ; i, an intercalary cell ; 

 b, the basal cell of the chain; p, the potential fficiospores which are being modified into 

 peridial cells. Note the wall markings and the long degenerating intercalary cells. 

 X 400. 



B. — A drawing of a section through a mature peridium, taken from the same series 

 as the photomicrograph in Plate 50, B. X 400. 



C. — A drawing of a short mature telial column in which the teliospores (a) have ger- 

 minated, producing promycelia and sporidia (6). See Plate 57 for details of the pro- 

 cess. X170. Drawn by Miss Minnie W. Taylor. 



