Brinkman and Szent-Gyorgyi1 report that various capillary active substances, alkaloids2 and purine bases (sodium oleate, sodium linoleate, sodium glycocholate, digitonin, Witte's peptone, atropine, pilocarpine, caffeine, strychnine, quinine and morphine) cause permeability of collodion membranes to hemoglobin. Rosenthal3 states that sodium taurocholate possesses the property of increasing the degree of permeability of semi-permeable collodion membranes to dyestuffs. Clausen has shown the presence of some capillary active substance in blood serum4 and urine of patients suffering from parenchymatous nephritis (nephrosis) which greatly lowers the surface tension, and reports that the addition of blood serum, urine, or, a water solution of the alcohol soluble portion of the colloidal residue from evaporated urine of these patients, will cause collodion membrane to become permeable to proteins.5 Grollman6 finds that the collodion sacs used in his investigation were not rendered permeable to hemoglobin by use o...