TJBEBINEM. 



311 



hyphae, which penetrate between the cells, causing the leaves 

 to become usually much thickened and distorted in those 

 parts which are infested with the parasitic growths. Oc- 



Fig. 216. — Several stages of Pwxinia graminia. A, part of a vertical section of a 

 leaf of the Barberry (Berberis vulgaris), with a young unopened secidium fruit ; u, 

 epidermis. /., section of a Barhen-y leaf, natural thickness at X, greatly thickened 

 from A towaid y ; u, epidermis of the under surface ; o, of the upper surface ; », 

 unopened secidium fruit ; a, a, n, opened ajcidium fruits ; sp, sp, epennagonia. 77., 

 a mass of teleutospores on a leaf of Couch-grass {Tntieum repens) ; «, the ruptured 

 epidermis : ft, sub-epidermal fibres of the grass leaf. III., three uredospores, ur, 

 with one teleutospore, t; sJi, subhymenial hyphae. All highly mignifled.— 4 and /. 

 after Sachs ; //. and III. after De Bary. 



casionally these byphse are found in other parenchymatous 

 parts besides the leaves, as the petioles, young stems, and 

 even the flowers and fruits. After a short time there form 



