II. ^ECIDIOMYCETES. 



PUCCIJVIA GRAMIN1S (^Ecidium Berberidis), 

 (Rust of Wheat). 



A. Puccinia Stage. 



I. There may often be found on the stems and leaves 

 of wheat and others of the Graminese in winter, dark 

 oblong patches, which owe their origin to a Fungus 

 (Puc'cinia graminis) that infests the tissues, and pro- 

 duces the disease called Rust. 



Examine one of these patches with a lens, and note 

 that the superficial tissues of the wheat are ruptured 

 by a longitudinal slit, and the torn edges are turned 

 back, so as to expose a dense, dark -coloured mass, 

 which protrudes from within : the nature of this mass 

 must be studied by means of sections. 



II. Cut transverse sections of the leaf-sheath, or other 

 diseased part of the Grass plant, taking care that the 

 section shall traverse one or more of the dark patches 

 of Rust : mount in glycerine, and examine under a low 

 power. Observe that the structure of the greater part 

 of the section is normal (see Part I. page 114, &c.) : 

 the dark patches will be seen to be opposite one of the 

 spaces between the vascular bundles, while the epider- 



