PLATE XXXVII 
Fig. i.—Lenticel in ripe fruit of Sapa plum. The walls of the cells lining the cavity 
give the staining reaction of cellulose. X 400. 
Fig. 2.—Lenticel in ripe fruit of Gold plum partially filled with parenchymatous 
cells. Infection may take place through a lenticel of this type. X 400. 
Fig. 3.—Lenticel in green Burkank plum. The cell walls lining the cavity give 
the staining reaction of cork. Infection may take place through a lenticel of this 
type, but only in the manner shown in Plate XXXVIII, figures 1,3, and 5. X 400- 
Fig. 4.—Lenticel in green fruit of B X W21 completely filled with parenchymatous 
tissue. Infection can not take place through a lenticel of this type. X 400. 
Fig. 5.—Ripe healthy tissue of Sapa plum, showing middle lamella completely 
dissolved out owing to ripening process. This is the condition found in the ripe fruits 
of the susceptible varieties. X 60. 
Fig. 6.—Ripe healthy tissue of Reagan plum two weeks after picking. The middle 
lamella is still intact. This is the condition found in the ripe fruit of resistant varie¬ 
ties. X 60. 
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