PLATE 49 

 Cronartium ribicola: 



A. — The edge of a pycnium in section. Note the position of the pycniunt' with 

 reference to the overlying periderm and underlying cells of the outer cortex. X 250, 



B. — Part of the same section showing the general relation of the elements which go 

 to make up the sorus and their relation to the host cells beneath, a, Contributing 

 hyphse; 6, pseudoparenchyma layer; c, sporophores. Compare PI. 58, A. X 1,050. 



C. — Tangential section in the xylem, showing the cut end of a ray and the manner 

 in which a haustorium (a) may rise from the hyphse in the ray and enter the lumen of 

 the tracheid. X 525. 



