Injection of adrenaline in ten daily doses of 100 micrograms each into the chequered water-snake, Natrix piscator, stimulated glycogenolysis and lipid esterification in the liver and lipolysis in the adipose tissue of control snakes. In both thyroidectomized and control snakes plasma protein levels decreased significantly after hormone treatment, although there was no change in concentrations of muscle glycogen and plasma lactic acid. In thyroidectomized snakes, the hormone stimulated oxidation of the free fatty acids but had no significant effect on the synthesis of the triglycerides. It is suggested that in these snakes the presence of the thyroid hormones is a prerequisite for the response of most of the metabolic processes to adrenaline.

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Thyroidectomy decreased the body weight and the height of the cells lining the sex-segment of the kidney of the Chequered Water-snake, Natrix piscator maintained at 30 \ s=deg\ C; at 40 \ s=deg\ Cthe liver, kidney and gonad were also affected. At the higher temperature, thyroidectomy influenced significantly protein, carbohydrate and lipid metabolism. At 30 \ s=deg\ C, only a decrease in the rate of esterification of the free fatty acids in the liver and of their release from the adipose tissue was observed. The difference in the effect of thyroidectomy at 30 and 40 \ s=deg\ Cis explained by suggesting that thyroid activity was low in animals maintained at the lower temperature and high in those kept at the higher temperature.

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In the water-snake, Natrix piscator, the following are depressed by orchidectomy and restored to normal by testosterone treatment: glucose, free and esterified fatty acids and triglycerides in plasma, hepatic triglycerides, and total esterified fatty acids. The increase in hepatic free fatty acids and muscle glycogen was also reduced to the level found in intact snakes. Moreover, although castration had no effect, testosterone caused a significant increase in liver weight and plasma protein, and a significant decrease in free plasma cholesterol. Except for an increase in triglyceride content by high doses of the hormone, neither castration nor the administration of 5 mg testosterone had any significant effect on the free fatty acid and triglyceride content of the adipose tissue of the snakes.