Cellular DNA content in different species of Xenopus

1. Biochemical methods were applied to determine the DNA content per cell in ten species and subspecies of Xenopus. 2. Cell density and DNA concentration were measured in a suspension of blood cells. 3. DNA was determined by the diphenylamine method and values were compared with those obtained by the ultraviolet absorption method and by cytofluorometry. 4. A good degree of reproducibility was demonstrated by a simple biochemical method which yielded values compatible with cytofluorometry. 5. Results suggested that the DNA of Xenopus muelleri, and perhaps that of other species with a large genome size, may be specially protected from chemical degradation.