1. A method is described by which the food intake of axolotls during a given period can be compared with their growth during the same period.
2. The method has been applied to animals injected with growth-promoting hormone.
3. The ratio food intake/weight gained has been calculated for batches of ten axolotls injected with muscle extract, Schockaert's extract of anterior pituitary, phyone, prolactin (Bates & Riddle, 1935), prolactin plus phyone.
4. This ratio was 2.66±0.20 for animals injected with muscle extract, 1.47±0.12 for Schockaert's extract, 1.60±0.11 for phyone, 2.21±0.16 for prolactin and 1.68±0.12 for prolactin and phyone together.
5. The effect is attributed to increased nitrogen anabolism.