Abstract
Rabbits were immunized with frog or tadpole haemoglobin purified either by chromatography or by polyacrylamide gel electrophoresis. The obtained rabbit antisera were shown to be specific for frog or tadpole haemolysates by double diffusion, immunoprecipitation and immunofluorescence. Indirect immunofluorescent staining of peripheral blood smears of Rana catesbeiana tadpoles at the metamorphic climax revealed that 16 % of the red cells were stained with antibodies against frog haemolysates, while almost all of them (98 %) were stained with antibodies against tadpole haemolysates. These results are compatible with the possibility that some of the circulating red cells in metamorphosing tadpoles contain both tadpole and frog haemoglobins.