Our knowledge of the endocrine functions of the pituitary gland is comparatively recent. Text-books of physiology published in the late 19th century (e.g. Michael Fost Text-Book of Physiology, 1891 edition) gave a good histological description of the gland, emphasised its ductless nature, but could attribute no definite function to it. The first evidence suggesting any function for the pituitary body was presented by Oliver and Schäfer in 1895. They observed that extracts from the whole pituitary gland had a pressor activity when injected intravenously into the anaesthetised dog. Howell (1898) showed that the substance responsible for this pressor action of pituitary extracts was obtainable only from one part of the organ, and rather surprisingly, only from its posterior, neural lobe. At the time this appeared to be quite an anomalous finding, as the main glandular structures were known to be localised to the anterior lobe of the pituitary.