RELATION BETWEEN THE CONCENTRATION OF THIOUREA SOLUTION AND ITS MASCULINIZING EFFECT ON FROG LARVAE

1. The tadpoles of Rhacophorus schlegelii, 30 or 40mm in length, were treated with a 0.1, 0.05, or 0.025 per cent thiourea solution, and the relation between the concentration of thiourea and the masculinization of the tadpoles was studied.2. The thiourea-treated larvae were killed 3 weeks after the time of metamorphosis of control animals. The sex ratio in the 0.025 per cent series was 1: 1, while in the 0.1 per cent series the number of male individuals remarkably increased. It is, therefore, conceivable that the masculinization in the thiourea treated larvae was increased with the concentration of thiourea solution.