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In the endocrine pancreas of eight species of Chalcides four types of endocrine cells (designated A, B, D, and PP or F) were revealed by immunocytochemical methods. A cells were immunoreactive to anti‐glucagon serum: B cells to anti‐insulin serum; D cells to anti‐somatostatin serum; PP cells to anti‐pancreatic polypeptide serum. In the splenic lobe, where endocrine cells are mainly concentrated and form large insular masses, A cells represent the most abundant type and PP cells are very rare or absent. In the ventral lobe, con taining small endocrine islets, all four endocrine types are present. However A, B, and D cells are preferentially located in the median region, while PP cells are numerous in the lateral region, where they appear isolated or associated in small groups scattered in the exocrine parenchyma. It was suggested that this regional distribution of the endocrine cell types reflects the different em bryonic origin of the two pancreatic lobes and/or different cell fun ctions.

Morphological changes are reported in the endocrine pancreas of the lizard Podarcis s. sicula after insulin and ACTH administration. After short term insulin administration both A and B cells appeared hypertrophic and stored large quantities of secretory granules. Chronic insulin administration led instead to a progressive degranulation of both kinds of insular cells, mainly with the A cells. During ACTH administration, B cells showed progressive degranulation while A cells remained almost completely unaffected. The possible mechanisms of pancreatic hormone release after insulin and ACTH administration are discussed.

The authors have studied the effects of insulin and glucagon administration on the blood glucose levels of the lizard Podarcis s. sicula Raf. during the winter. The administration of insulin induces hypoglycaemia with the blood glucose levels reaching a minimum after 3 injections of 4 IU of insulin and a subsequent partial recovery during the course of the treatment. Glucagon treatment on the contrary causes a strong hyperglycaemia which is dose‐dependent and reaches the maximum values about 2.30 hours after the administration of the hormone. The hyperglycaemic action of glucagon is evident also in specimens previously treated with insulin. The glucagon action is not long lasting and the blood glucose levels become normal within 24 hours of the administration of glucagon.