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ROSEr-BLISTER CANKER 



119 



Fig. 4. — Oxidation by mixtures of diseased bark, pyrogallol, and various buffer 

 solutions: A, after 23 hours (shaken 2 hours of this time) ; B, after 45. 5 hours; C, after 

 69.5 hours; A and B as in fig. 3. 



