Bui. 1120. U. S. Dept. of Agriculture. 
PLATE IV. 
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B 
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Photomicrographs of Cross and Longitudinal Sections of Stems of 
Heat-Cankered Flax Plants of the Same Age as Those Shown in 
Plate III. 
A , injured, constricted area oi' plant. This cross section sliows the entire eorle.x destroyed. The 
cortical cells are broken down, but the stelar ti'^sues are still functioning. There is no evidence ol 
fungous mvcehum in the injured tissues. Compare this with B. B, cross .section immediately 
above the cankered area. All lis.sues appear healthy. Compare this with A. C, longituduial 
section through the upi)er portion of an injured, constricted area. This shows the cortex d(>- 
stroj-ed in the cankered area. D longitudinal section of a young flax stem immediately above 
the heat-cankered area. 
