THE EFFECT OF CERTAIN CONDITIONS UPON THE 
ACIDITY OF TOMATO FRUITS 
B. M. DUGGAR 
Physiologist to the Missouri Botanical Garden 
Professor of Plant Physiology in the Henry Shaw School of Botany of 
Washington University 
AND M. C. MERRILL 
Research Assistant to the Missouri Botanical Garden 
In а recent communication the senior author (4) has referred 
to the possibility that the total acid content of tomato fruits 
ripened at a temperature of 30°C., or above, may be related 
in some way to the failure of lycopersicin development at that 
temperature. It was determined that the ''total acidity for 
green, ripening, and ripe fruits, grown under the same condi- 
tions, is unexpectedly uniform, amounting to .57 to .58 per 
cent citric acid." The fruits just referred to were of the 
same variety picked at the same time. Тһе tests of acid con- 
tent of incubated fruits were made later in the season, and 
these indicated a lower acidity than that of normally green or 
ripe fruits. At that time the requisite material was obtained 
from the Department of Horticulture, Cornell University. 
During the past summer several varieties of tomatoes were 
grown in the Missouri Botanical Garden in order to furnish 
material for further pigment studies, and incidentally this 
material has enabled us to determine with greater care the acid 
content of tomato fruits, especially of different varieties, and 
likewise the comparative acidity of fruits direct from the field 
and of those of the same picking incubated for various intervals. 
The tests included below were made by pulping thoroughly 
а weighed quantity of the tissue (15 gm.), diluting with 150 
сс. distilled water, employing for each titration 25 сс. of this 
solution diluted with distilled water to 50 cc., and titrating 
with n/10 NaOH, using phenolphthalein as indicator. Not less 
than two titrations were made in any case, and these were from 
one or more samples of tissue. Тһе accompanying table 
ANN. Мо. Вот. GARD., Vor. 1, 1914 (237) 
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