PLATE 23 ' 



A. — Portion of the typical crooked, irregular mycelum with numerous haustoria 

 which is found in the mesophyll of badly infected leaves, here freed from the host 

 tissue by maceration. X 375- 



B. — Longitudinal section cut from the center of a maize stem 8 inches from the 

 ground. The plant, over 5 feet in height, was just putting out its tassel and had 

 recently shown markings of the disease on its four uppermost leaves. A strand of the 

 mycelium can be seen running alongside the bundle between cellsof the biindle sheath 

 which are penetrated by numerous haustoria. X 375- 



C. — Portion of the mycelium freed by maceration from tissue of the midrib at the 

 base of a badly infected leaf. X 375- 



D. — Hypha cut in cross section as it lies between three adjacent mesophyll cells of 

 the host. The penetration of a characteristic haustorium into one of the host cells is 

 shown. X 850. 



E. — Transverse section from a badly infected portion of a maize leaf, showing the 

 abundant mycelium running between the cells of the bundle sheath and forming in 

 the substomatal air chamber the branches (a) that grow out through the stoma to form 

 the conidiophores. The haustoria are seen penetrating not only the mesophyll cells 

 but also a cell of the xylem (b) and the epidermis (c). X 375- 



F. — Portion of a hypha lying between adjacent mesophyll cells, one of which has 

 formed a many-layered wall around the haustorium invading it. X 850. 



G. — Portion of a hypha similar to that shown in F but with the haustorium unhin- 

 dered in its invasion of the host cell. X 850. 



H. — Bit of mycelium such as is shown in A but more highly magnified to show the 

 haustoria. X 850. 



• The drawings were made with the aid of a camera lucida and are all from preserved material of maiz e. 



