Abstract
Laparotomy or hypophysectomy does not change the blood-sugar level in Mustelus canis. Pancreatectomy produces a marked hyperglycemia, which, however, is less marked if pancreatectomy is ac companied by hypophysectomy, but slightly more marked if in addition to pancreatectomy the hypo thalamus is injured. It is concluded that the hypophysis exerts an aggravating influence on the pancreatic diabetes of M. canis, a result similar to those reported by other authors for dogs and toads.