Heat-Induced Triploidy in the Newt, Triturus Viridescens

Abstract
Following earlier work on the production of triploidy in newts by cold, 113 freshly laid and fertilized eggs were placed in temps. ranging from 34.2[degree] to 37.2[degree]C for 5-50 min. and then raised at room temps. Of those that developed, 49 (79%) were triploid. The shortest effective periods were 5 min. at 37[degree] and 8 min. at 36[degree]. Short heat treatments are at least as effective as long (5 or more hrs.) cold treatments and the mortality possibly lower. Both heat and cold presumably act by suppressing the 2d maturation division which is not completed until about 1 hr. after fertilization.