732 



FUNGI 



produce the fungus there. However, if they are carried by 

 the wind or other means to the leaves of wheat plants, each 

 aecidiospore produces one or two germ-tubes which enter through 

 the stomata of the wheat leaves and give rise to a mycelium 

 from which uredospores are produced. 



We thus observe that during its life-cycle the fungus bears 

 three different forms of chlamydospores, namely, secidiospores 

 on the barberry in spring, uredospores on wheat in summer, and 

 teleutospores in late summer also on wheat. The two former 



Fig. 248. — A , .^Ecidia or ' cluster-cups ' of Puccinia coronata Corda. on a leaf of 

 black alder {Rhancnus Frangula L.) (10 times natural). 



B, Transverse section through a leaf of black alder infected with P. coronata : 

 a spermogonium of the fungus ; / peridium of the jecidium or cluster-cup ; s free 

 aecidiospore. (Enlarged 60 diameters.) 



kinds of spore are single cells and germinate immediately with 

 the formation of a simple hyphae, while the latter are bicellular 

 resting-spores which only germinate after hibernating several 

 months, and then produce basidia bearing basidiospores instead 

 of simple vegetative hyphse. Before any relationship between 

 them was known, the three stages of the fungus were referred 

 to as three distinct species belonging to the genera Vadium, 

 Uredo, and Puccinia respectively. 



