Bui. 82, U. S. Dept. of Agriculture. 
Plate I. 
* 
B«3 
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h. 
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y 
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■-,.¥' 
n; v 
Various Stages in the Life History of the Fungus which Causes 
Powdery Scab. 
A, A large host cell in which there are three amoeba? of Spongospora. B, A young host 
cell in the early stages of infection. The amoeba lies just below the nucleus. C, The 
amoebae are coalescing to form the Plasmodium. D, The plasmodial stage. E, Mature 
spore balls in an enlarged host cell. (.4 to E, after Osborn.) F, The isolated spore 
balls photographed. Note the variation. (Original.) 
