Excerpt from The American Journal of Physiology, 1899, Vol. 2 In considering the immediate antecedents of kynurenic acid tyro sin is at once suggested. The behavior of this aromatic compound with reference to its possible synthesis to oxyquinoline-carboxylic acid in the body has been investigated by Hauser3 and Solomin,4 both of whom failed to obtain evidence of any direct relationship between the two substances. Plan of present investigation. - The present investigation is an attempt to ascertain something more definite regarding the condi tions which determine and modify kynurenic acid production and excretion. Unless otherwise stated, the data have been obtained with dogs. The animals were kept in suitable roomy cages which permit the separate collection of urine and faeces, and stand in a light, well-ventilated space. It was not found necessary to resort to catheterization, since the periods of observation always extended over more than one day and the animals soon became accustomed to discharge their urine with considerable regularity. The nitrogen was determined in the urine and diet by the Kjeldahl method; sugar, when present, was estimated by titration with Fehling's or Purdy's solution,5 and kynurenic acid was found by the method of Capaldi,6 which has proved very satisfactory. The product thus obtained always responded to Jaffe 5 test7 and was crystalline; in a few urines a very small quantity of an amorphous substance was precipitated. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.