10 



FIG. i. Puccinia graminis, an heteroecious fungus producing 

 different kinds of spores on different hosts, and on the same host at 

 periods, i, leaves of wheat plant with pustules of uredospores ; 2, a 

 pustule or group of uredospores more highly mag. ; 3, uredospores in 

 various stages of development ; 4, uredospore germinating ; 5, portion of 

 a wheat stem showing pustules of teleutospores ; 6, teleutospores in 

 various stages of development ; 7, teleutospore germinating ; 8, a bar- 

 berry leaf bearing groups of the aecidium or ' cluster-cup ' form of fruit ; 

 9, section of an aecidium containing spores in chains ; 10, two aecidia 

 seen from above ; n, sporules from a spermogonium. All figs. mag. 



