Biology of the Uredinea. 3 
3. The promycelial spore may give rise to a mycelium 
which produces, first, spermogonia, then zecidiospores, 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 zcidiospores and teleutospores (Pucciniopsis), 
or the spermogonia and zxcidiospores 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 fEcidiospore — 
Teleutospore Uredospore ~ 
Teleutospore - 
