Little is known about the part histamine plays in different non-allergic disorders, although there are some observations on animals suggesting a correlation between tissue histamine and thyroid activity (Goltz & Dragstedt, 1940;Hoffmann & Hoffmann, 1944). Further, one of us observed that in hyperthyroid women there is a lower incidence of malignant growth of the breast than among the average female population, and discussed the possibility of a relationship between tendency to malignant growth and histamine content of the tissues (Loeser, 1953(Loeser, , 1954a.So far Harris (1927) seems to be the only author who has made a more detailed determination of the histamine equivalent of extracts prepared from human skin by assaying their depressor action on the cat's arterial blood pressure against histamine. The histamine equivalent of skin samples taken from nine breasts was found to be between 5-7 and 7-6, and from three thighs between 8 and 8'8 pug/g. The number of his cases was rather small and in our greater number of patients more individual variation in the histamine equivalent of skin was found than was to be expected from his results. METHODSThe skin was removed during operations or excised under local anaesthesia and transported, straight after removal, from the operating theatre to the laboratory, where it was freed from loose subcutaneous tissue and fat, weighed, and minced in a mortar with a little sand and acidified (HCI) 0-9 % NaCl solution. The samples weighed between 30 and 300 mg. The minced extracts were boiled for a minute, filtered, neutralized with NaOH, and assayed against histamine on the atropinized guinea-pig's ileum preparation. All histamine values refer to the base. The time between removal of the skin and extraction was usually less than 1 hr. Sometimes the skin of the same patient was re-examined after special treatment. Table 1 summarizes the results obtained, in the course of 40 months, from forty-nine patients, arranged in ascending order of histamine values which vary between 1V8 and 26-7 ,ug/g (mean 8-8 ,g/g). All skin samples except two were from women. RESULTS

No abstract