220 
R. B. HARVEY 
Summary 
It was found that the concentration of osmotic substances was the same 
in tumor and healthy tissues in Ricinus and beet when measured by the 
thermocouple method. Hence osmotic relations do not account for the 
tumor production by Bacterium tumefaciens in these cases, 
Catalase, oxidase, and peroxidase activity is greater in tumor tissue 
than in adjacent healthy tissue either when the tumors are produced by 
inoculation with B. tumefaciens or by freezing. 
Growth in frozen spots of Bryophyllum leaves is correlated with the 
accumulation within them from the surrounding tissue of substances of the 
nature of catechol, which are transformed by oxidation into colored com- 
pounds. 
The H+ concentration of tumors produced both by freezing and by 
bacterial inoculation is consistently less than that of adjacent healthy tissue. 
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