Unique alpha-cell crystals, a herpes-like virus, islet amyloidosis, and immunohistochemical reactions of islets are compared in the rodent, Octodon degus, in animals with ordinary and high circulating glucose levels. Results suggest that crystals, virus, and amyloid are independent of blood sugar and bear no obvious relation to one another, although each is more common in older than in young animals. The crystals do not react with anti-glucagon. In the presence of high blood glucose, qualitative histochemical studies demonstrated diminished islet insulin and an unusual reaction with anti-somatostatin: (1) paucity of the usual cells that stain darkly for somatostatin and (2) striking staining of intermediate hue in most islet cells and in (3) multitudes of cell nests in exocrine parenchyma. The intermediate staining reaction may represent a visible demonstration of the paracrine phenomenon.