PLATE 4 
Puccinia graminis tritici form III on Mindum 
A. —Three days after inoculation. Longitudinal section of stoma bearing apptes- 
sorium. Both outer and inner walls of guard cells modified. X730. 
B. —Seven days old. Appressorium d dying, guard cells dead, adjoining walls of 
epidermal cells swollen, and nearest mesophyll cell a dying. The fungus has not 
entered. X730. 
C. —Two-day infection. Two sections. Head of stoma and part of infecting hypha 
in Cj; rest of hypha, haustorium mother cell a and young haustorium h in C 2 . Plastids 
and nucleus of host cell collecting around haustorium. X1460. 1 
D .-Two-day infection. Slightly later. Haustorium mother cell at s collapsed and 
dying. Nucleus and cytoplasm of host cell concentrated about haustorium a, leaving 
two lobes of the cell c and d empty and collapsed. X1460. 
