Bui. 82, U. S. Dept. of Agriculture. 
Plate II. 
^ B 
Four Tubers [A, B- C, and D) Infected with Spongospora Subterranea Col- 
lected in New Brunswick, Dominion of Canada, on October 1, 1913. 
They represent the scabby stage of the disease. The sori may be either isolated or grouped, 
as' shown in A and B. The variation in size and general appearance of the sori is 
brought out in Cand D. In the tuber marked D the sori are only about half as large 
and more superficial than in C. Two tubers infected with Oospora scab are show r n as 
E and F. 
