[Utilization of CoCl2 for karyological studies in teleosts]

This paper presents a simple method of increasing the number of mitoses in the kidney of fish. This method is based on the erythropoietic activity of CoCl2. The specimens of Ictalurus sp. were injected intraperitoneally with 2 mg CoCl2 per 100 g body weight. After 24 h the slides of kidney show a proliferation of erythroblasts. A large number of these cells are arrested in metaphase for karyotype preparations.