The nucleus preopticus (NPO) of the normal goldfish examined at intervals of three hours for a complete day exhibits marked variation in their affinity for aldehyde fuchsin (AF). Some times in this nucleus the cells of the pars magno-cellularis were deeply stained while those of the pars parvocellularis were lightly stained, which suggests a functional difference. Both NPO and the nucleus lateralis tuberis (NLT) are AF-positive in the goldfish. In the neurohypophysis three tinctorial types of Herring bodies were seen; the AF-positive bodies can be traced back to the NPO but the origin of the fast green and acid fuchsin bodies is uncertain. In the hypophysectomized specimens without regenerating neurosecretory axons the NPO exhibited degenerative changes. However, if regeneration of the pituitary stalk occurred, forming a neurohypophysis-like organ the NPO was apparently normal. Prominent AF-positive granules were not obvious in the NLT of hypophysectomized specimens.