The citric acid content of animal tissues, with reference to its occurrence in bone and tumour

THE distribution of citric acid in the animal body has not previously been systematically studied, for although Thunberg and his colleagues have made a careful examination of the citrate content of body fluids, that of the solid tissues has been largely neglected. This is all the more surprising, since Pucher et al. 1936 have described a sensitive colorimetric method which, unlike the enzymic one of Thunberg, is readily applicable to such material. Pucher et al. 1936 and Sherman et al. 1936 analysed only a few tissues by the colorimetric method (liver, kidney, abdominal and heart muscle of the dog), for which very low values were found (0-119 mg. citric acid/100 g. tissue). It is clear from their paper that they regarded these results as typical of the major tissues of the body, but this view is shown to be incorrect by the present work.