Biology of the Ui'ediucce. 



3. The promycelial spore may give rise to a mycelium 

 which produces, first, spermogonia, then aecidiospores, then 

 uredospores, and finally teleutospores (Auteupuccinia). 



Certain minor variations in the life-cycle occur ; for 

 example, the uredospores may be suppressed, so that we 

 have only aecidiospores and teleutospores (Pucciniopsis), 

 or the spermogonia and aecidiospores may occur on one 

 plant, and the uredospores and teleutospores upon another 

 of a totally distinct kind (Heteropuccinia). 



Each of the above spore-forms has its own peculiarity 

 of structure, as well as origin, so that it will be better, for 

 clearness, to describe them separately. 



The spore relations may be thus tabulated : — 



Promycelial Spore. 



Teleutospore Uredospore Spermogonium Spermogonium 



Teleutospore Uredospore ^cidiospore 



Teleutospore Uredospore 



Teleutospore 



