304 



PtTCCINIA. 



Scrape off some of the " rust," and note the numerous 

 uredospores, each consisting of an ovoid cell with a thick 

 outer coat (covered with fine spines when mature) ; the 

 inner layer is thinner ; the spore contents are coloured 

 with drops of orange or yellow oily matter. Note the 

 four pits or thin spots, situated at regular intervals 

 round the equator of the spore at each of these spots 

 the endospore is interrupted so that the cell-contents are 

 in contact with the exospore, the latter being also thinner 

 at these spots than elsewhere. 



Examine transverse sections of Wheat stem, leaf- 

 sheath, or leaf, bearing patches of uredospores. Note 

 (1) the patch corresponds to a region between two of the 

 hard bundles below the epidermis ; (2) the epidermis is 

 broken through at each side of the patch ; (3) the 

 mycelium of the Fungus consists of slender threads 

 traversing the soft parenchyma tissue and forming a 

 denser layer just below the patch ; (4) each uredospore 

 is borne on a slender stalk forming an outgrowth of the 

 mycelium. 



437. Teleutospores on Wheat (Fig. 64). Later in 

 the year, from July onwards, note that the " rust " patches 



Fig. 64. PUCCINIA. Part of a Transverse Section of Wheat Leaf, with 

 Teleutospores of Puccinia. 



become blackish instead of orange, especially on the stems 

 and leaf-sheaths. This is due to the fact that the 

 mycelium is now producing spores of another kind instead 



