1. 1.|The metabolic role of the thyroid gland was studied in intact snakes, Naja naja and Ptyas korros treated with tri-iodo-thyronine (T3) and thyroxine (T4) and in thyroidectomized (Tx) N. naja kept at 21°C by analyzing tissue composition and glycogen phosphorylase a activity.
2. 2.|Liver weight was unaffected by thyroid hormone injection in both species but decreases in liver glycogen followed T3 or T4 injection, and there was an increase in liver glycogen in N. naja. These changes in liver glycogen were accompanied by a decrease in glycogen phosphorylase a activity with T3 injection. T3 decreased muscle glycogen in Ptyas and Tx increased it in N. naja.
3. 3.|T3 increased % liver lipid in Ptyas but not in Naja.
4. 4.|Between species, there were differences in liver weight, blood glucose level, cholesterol level and % muscle lipid.
5. 5.|The results showed that thyroid hormones affected carbohydrate and lipid metabolism at a low temperature of 21°C, although the significance is not known.