A number of clinical observations and experimental investigations prove that impairment of function of, or experimental injury to the hypothalamus is connected with functional change of the hypophysis and with changes in the endocrine system (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(20)(21)(22)(23)(24)(25). The correlation between the hypothalamus and neurohypohysis is most marked through neural connections (17, 18, 19). It is also well known that the removal of the neurohypophysis i. e. the cutting of the pituitary stalk involves degeneration of the hypothalamus (26-34). On the other hand electrical stimulation of the hypothalamus is followed by mobilisation of the antidiuretic hormone (36). So we may justly say that the function of the neurohypophysis can not be imagined without an integral hypothalamus and its hormone-production is controlled by the hypothalamus as a superior endocrine centre (22, 23, 35).Other investigators have demonstrated that the secretory product of the hypophysis streams along the nerve fibres directly into the brain (37-41, 120, 121). It has also been suggested that the hypothalamus beside its neural function possesses also a hormone-productive capacity (42, 114, 118, 119). Abel (43, 44) was the first to establish antidiuretic substance in the hypothalamus of sheep, later other authors confirmed his results on dogs and rats (45-49). Other hormone-like substances have also been investigated. It became obvious that only hormones of neurohypophyseal effect could be demonstrated to a considerable extent in the hypothalamus, while adeno-hypophyseal hormone-like effects were t o be found only in traces (50). Rioch (51) however is of the opinion that hormones of pituitary effect are not to be found in the brain or if present a t all then only in insignificant quantities.