INDUCTION OF TRIPLOIDY AND HAPLOIDY IN AXOLOTL EGGS BY COLD TREATMENT

Abstract

1. One hundred and fifty-four eggs of the white race of axolotls were refrigerated shortly after fertilization, at + 1° C. to + 3° C., for from nine to 24 hours, and raised at room temperature. 2. Thirty-one larvae were obtained from refrigerated eggs. Twenty-five of these were triploid, five diploid, and one haploid. The triploid larvae presumably arose from eggs in which the exposure to cold had suppressed the second maturation division. The origin of the haploid larva is unknown. 3. Of 148 control larvae, 147 were diploid and one triploid. 4. Seventeen of the triploid larvae, as well as the five diploid larvae which developed from refrigerated eggs, were more or less abnormal, presumably because of a general harmful effect of the low temperature on the eggs. This was also responsible for the high mortality among treated eggs before and during cleavage. 5. Seven of the remaining eight experimental triploids, as well as the single spontaneous triploid, are normal in size, appearance, and viability. 6. Experimental induction of triploidy in axolotls is of particular interest because it may make it possible to raise triploid individuals to sexual maturity and to carry out breeding experiments.