LIFE HISTORIES OF FUNGI 275 



wind to the leaves of nearby barberry bushes, where they 

 germinate. The resulting mycelium penetrates the epi- 

 dermis, and ramifies between the cells of the leaf paren- 

 chyma, from which it absorbs nourishment. Under 

 certain circumstances, as for example in Australia where 

 barberries do not grow, the barberry stage is eliminated. 

 Soon this mycelium develops a reproductive structure 

 called the pycnium (pycnidium or spermagonium), which 

 breaks through the upper epidermis and produces innu- 

 merable pycnios pores (spermatia). The real nature of 

 this structure is not known. 



OUTLINE OF LIFE HISTORY OF WHEAT RUST 

 Rust on Grain 





Near the lower epidermis are formed the "cluster- 

 cups," or acid 1 (aecidia). They break through to the 

 1 Sing, cerium. 



