PLATE 2 
A. —Portion of 4-day mycelium showing a “runner” at a and a', haustorium mother 
cells at b and e, and a young haustorium at c forming from the cell d. 
B. —Hypha, forcibly checked in growth by striking host cell, preparing to form 
haustorium. 
C. —Similar but slightly older. The tip of the hypha is swollen, the pair of nuclei 
have divided, and one daughter pair has moved to the tip. At b, a slightly later stage. 
D. —Septum formed a short distance back from the tip of hypha, forming the haus¬ 
torium mother cell. Its nuclei have decreased in size. Branch forming from hypha 
behind. 
E. —Beginning of haustorium formation. The young haustorium is a peglike pro¬ 
jection into the host cell. Mother cell very dense. 
F. —Slightly older haustorium differentiated into neck and body. Mother cell still 
dense in content. 
G. —Larger haustorium, still invested with a sheath of host cytoplasm. Contents 
of haustorium mother cell less dense. Its nuclei much smaller than those of hypha 
behind. 
H. —Entire contents of haustorium mother cell emptied into haustorium. 
I. —Larger haustorium with denser core and heavy envelope of host cytoplasm, 
including a plastid at a. 
Drawings were made from preparations of Puccinia graminis tritici on Baart. 
