THALLOPHYTA— FUNGI 



89 



easily transported by the wind. It is incapable of developing 

 a mycelium upon the grass, but if it falls upon the leaf of the 

 Barberry, it germinates, sending a hypha through the epidermis, 

 instead of penetrating a stoma like the uredospore. The myce- 

 Hum resulting from this hypha forms a dense network m the inter- 

 cellular spaces of the leaf. At particular spots upon the leaf 

 brown pustules make their appearance, in which two kinds of 

 receptacles appear. Some on the upper surface of the leaf are 

 much hke the spermogonia of the Ascomycetes, and bear the 



Fig. 851. 



Fig. 852. 



Fig. 851. Group of three uredospores, ui\ and one teleutospore, t, springing 



from mycelium &h. Fig. 852. Section through leaf of the Barberry 



infested with Puccinia graminis. o. Epidermis of upper surface of leaf, 

 sp. Spermogonia. p,p. Layers of cells (^ertrfmm), surrounding a, a, the 

 fficidium fruits. After Sachs. 



same name. They produce spermatia in the same way as the 

 latter. Upon the under surface large spherical bodies are formed 

 (fig. 852), containing a hymenial layer of sterigmata which 

 cut off from their apices a succession of spores known as 

 CBcidiospores. There are large numbers of chains of these thus 

 produced in the globular mass, which is known as an mcidium 

 The whole Eecidium has a wall derived from the sterile hyphse 

 "When mature it ruptures and the spores escape. These are 

 carried in their turn to other grass plants, and there germinating, 

 reproduce the uredo form, entering the grass through the stomata. 



