The starting point for the investigations which are presented here, was the clinical Observation that a rise of blood sugar can occur in brain diseases and injuries. The extent and duration of this hyperglycaemia was variable and seemed to be related to the clinical severity of the neurological Syndrome. In addition the hyperglycaemia was associated with central dysregulation of the various autonomic functions (Pia 1973) such as blood pressure and pulse (Lorenz 1973), respiration (Seeger 1968), temperature (Lausberg 1970), as well as disturbances of the metabolism of water and electrolytes (Wesemann 1973) and the amino-acids (Bauer 1974). This would seem to indicate that the hyperglycaemia is but one part of a general reaction of the organism to particular acute lesions of the brain or is a component of a complete switch over of autonomic function and metabolism in arch to achieve a particular Performance. One is frequently able to establish a very close temporal relationship between certain acute brain lesions or complications after neurosurgical interventions and the extent of the hyperglycaemia which develops. The question which arises from this is, whether injury or Stimulation of any particular brain structures especially the diencephalon and brain stem are of significance.