1. The form of the temperature-glycogenolysis curve of frog's liver slices, when incubated with Ringer solution, was determined over the range 7-21° C. for samples of frogs over a period of 18 months. Three types of curve were observed:
(a) Low linear, interpreted as being the least complex form, in which the action of temperature is not complicated by other factors.
(b) Type B, which showed a disproportionate increase in glucose production above a certain temperature, attributed to the potentiation of sympathomimetic material.
(c) High linear.
2. Both the addition of adrenaline and noradrenaline to the incubation medium caused an increase in glucose production at all temperatures. Also, the disproportionate increase in glucose production of the type B curve occurred at a lower temperature in the presence of either of these agents.
3. Thyroxine had no effect on the form of the temperature-glycogenolysis curve, and there was no correlation between the state of activity of the thyroid gland and the type of temperature-glycogenolysis curve.
4. Glucose production of liver slices was lowered at all temperatures by the in vivo administration of insulin 19 hr. prior to an experiment. Insulin in vitro had no action.
5. Dibenzyline lowered glucose production of liver slices at all temperatures, and raised the temperature at which the extra glucose production, associated with a type B curve, occurred. The extrapolation of the lower portion of the mean curve after dibenzyline to 21° C. gave a line almost identical with the mean low linear curve.
6. The environmental temperature at which frogs were maintained prior to an experiment did not affect the form of the temperature-glycogenolysis curve.
7. The seasonal variation in liver-glycogen content was found to agree closely with the values obtained by Smith (1950).