The metabolism of the organic acids of tobacco leaves; effect of culture of excised leaves in solutions of organic acid salts.

In an earlier study of the effect of culture of excised tobacco leaves in darkness in solutions of a number of common organic acids (1)) it was noted that the behavior of the malic and citric acids in leaves cultured in (+)tartrate differed little if at all from that observed in the control samples cultured in solutions of inorganic salts. However, the so called “unknown acid” fraction, i.e. the acidity due to acids other than malic, citric, and oxalic, increased to an unusual extent. It accordingly seemed probable that tartaric acid is neither metabolized itself nor does its presence affect the metabolism of the normal organic components of the leaves under the experimental conditions. The development of chromatographic methods for the determination of the organic acid components of extracts of plant tissues has recently made it possible to examine this result more closely. It has been found that (+)-tartaric acid, the form of this substance which occurs in grapes and in a few other plant tissues,l is readily taken up by tobacco leaves as its