The Effects of Pituitrin and of Narcosis on Water-Regulation in Larval and Metamorphosed Amblystoma

Abstract

(1) Injection of post-pituitary extract to larval and adult Amblystoma individuals leads to an increased water-intake, followed by a decrease in water-content the body, the decrease being greater than the preliminary increase. Repeated injections cause decreases of body-weight of over 35 per cent. (2) This effect runs parallel with the chromatophore effect. No change in oxygen consumption could be detected, even with long continued injection. (3) Both larval and metamorphosed Amblystoma lose weight (by loss of water) when narcotised in a solution of amytal 1 : 3000; the loss is greater in larval specimens; the decrease is followed, in metamorphosed animals, by a slight net increase. (4) Both the pituitary effect and the amytal effect develop considerably more quickly in larval than in metamorphosed Amblystoma. (5) The mechanism regulating the water-equilibrium of the body in Amblystoma passes, during metamorphosis, from a relatively imperfect state in the larval stage to a more efficient condition in adult individuals.