SUMMARYAn agar‐gel immune haemolysis method was developed for detecting antibody in the lumen of tubular structures in tissue sections. It was used to show haemolytic antibody in renal tubules and blood‐vessels in immunized mice. Globulins and antibody were also found by gel‐diffusion precipitin and immunoelectrophoresis techniques in concentrates of urine from normal or from immunized mice.