Inducing Land Stage of Triturus viridescens to Assume Water Habitat by Pituitary Implantations

Abstract

The studies of Gage 1 and Pope 2 have shown the life cycle of Triturus viridescens to consist of 3 phases. (1) an aquatic larval stage of about 3 months' duration; (2) an immature, red-colored land stage, lasting from 2 1/2 to 4 years and, finally, (3) an aquatic adult stage. While there are some variations in this typical life cycle, apparently depending upon the locality, 3 , 4 the newt in the Blue Ridge Mountains of extreme Western North Carolina shows exactly the life cycle described by Gage and Pope, with a possible extension of the second stage into a fifth year.

The life cycle of Triturus is very interesting because of the 2 complete changes in habitat that take place. First, at 3 to 6 months of age, the metamorphosis from the aquatic larval to the terrestrial condition with the accompanying migration to land, and second, in the fourth to fifth year, the migration back to water as the animal approaches or reaches sexual maturity with consequent readaptation to a water habitat.

Metamorphosis among the Amphibia has been shown to be essentially an effect of the endocrine glands, particularly of the thyroid and indirectly the pituitary. 5 In our investigations on Triturus we have been interested, not in particular morphological changes, but in the relationship that might possibly exist between the endocrine glands and the phenomenon of migration from land to water and vice versa. Do the pituitary and thyroid glands, in addition to bringing about certain morphological changes, provide the “drive” which induces the change in habitat following metamorphosis? In seeking the answer to this question we sought first to determine the relation of the pituitary, if any, to the return of the land stage of Triturus to water.