RELATION OF CATALASE, OXIDASE, AND H+ CONCENTRA- 
TION TO THE FORMATION OF OVERGROWTHS 
R. B. Harvey 
Overgrowths were found by the author (7) to result from local freezing 
of the leaf tissue in a number of plants, including cabbage {Brassica oleracea 
capitata) and Bryophyllum calycinum. These overgrowths offer special 
opportunity for the separation of certain factors concerned in the re- 
juvenescence of cells, and for the comparison of physiological conditions 
attendant upon the production of overgrowths resulting from infection with 
Bacterium tumefaciens and from the stimulation of normal tissue by physical 
and chemical means. The literature of overgrowths as a result of bacterial 
infections in plants has been fully presented in papers by Dr. Erwin F. 
Smith. 
The economic importance (9, 19, 20) of certain plant diseases in which 
overgrowths are produced, and the relation of these to growths of similar 
nature occurring in man and other animals (3, 4, 5), have had sufficient 
discussion in recent articles (6) to make comment unnecessary in this 
paper. The production of intumescences by means in which bacteria are 
not concerned has been noted recently by Smith (2) and Wolff (i). 
In a paper by Dr. Erwin F. Smith (2, p. 167) it was suggested that os- 
motic relations between tumor and healthy tissues might offer an explana- 
tion for overgrowths. With a view to determining these osmotic relations 
the author has determined the freezing points of tumor and healthy tissues 
in different plants. It now appears that determinations referred to in a 
publication by Dr. Smith (3, p. 441) may be in error on account of the 
difficulty in obtaining the true freezing point of the tissues from the freezing 
point of the expressed juice. 
The freezing point of tumor and healthy tissues taken from the same 
plants was obtained by expressing the juice with a Buchner hand press, and 
with an hydraulic press using 10 tons on a 2^/2 inch ram. 
The freezing point of juices expressed from a tissue vary according to 
the treatment before expression and also according to the pressure applied 
(7, p. 94). Also, it appears that variation in the quantity of wood in the 
tissue prevents one from obtaining a uniform sample by pressure. 
In table i are given the freezing points of juices expressed after freezing 
with solid CO2 and grinding in a mortar while frozen dry. Stem tissue 
was taken from nodes immediately adjacent to the tumors. The tumor 
material was supplied by Dr. Smith's laboratory and was produced by 
inoculation with Bacterium tumefaciens. 
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