Comparison of the Chemical Composition of Aqueous Humor, Cerebrospinal Fluid, Lymph, and Blood from Frogs, Higher Animals, and Man

In the course of the quantitative studies of glomerular urine which have long been in progress in this laboratory, analytical methods requiring exceedingly minute amounts of fluid have been developed for a number of constituents of blood and urine. It seemed important to extend the application of these methods to certain other body fluids for the sake not only of the information which might be gained, but also of the influence which the results might have upon the credibility of the analyses of fluid from single renal units. The fluids chosen for study are lymph, cerebrospinal fluid, and aqueous humor. The analyses to which they have been subjected include determination of reducing substances, inorganic phosphate, uric acid, and urea. The results of analyses of lymph and cerebrospinal fluid of frogs were quite in accord with those of the majority of investigators who have analyzed these fluids in mammals. In the case of the aqueous humor of frogs, however, our results were so at variance with accepted ideas of the com-