Hyla versicolor (2n = 48) is a tetraploid counterpart to H. chrysoscelis (2n = 24). Cytochemical measurements revealed that no cytological parameter of the two species conformed to the expected 2:1 ratio. Every cytological factor of the tetraploid appeared to have been regulated toward the diploid level. H. versicolor-to-H. chrysoscelis mean ratios and their standard errors were: DNA, 1.90 ± 0.03; nuclear histone, 1.70 ± 0.18; nuclear RNA, 1.63 ± 0.19; total nuclear protein, 1.46 ± 0.05; nuclear sizes, 1.42 ± 0.08.