The functions of the eosinophil cells remain one of the mysteries of biology. Our knowledge of these cells includes their morphology, their place of origin and the naming of the various clinical conditions in which their number either in circulating blood or locally in the tissues varies from the usual. Of the rôle played by the eosinophil leukocytes in the economy of the body we know little. Experimental work has lagged far behind speculation in this field.
Some months ago a phase of the problem of the functions of the eosinophil cells was suggested by two observations. In 1910 a case of bronchial asthma came to my notice showing extreme blood-changes—a leukocytosis of 56,000, an eosinophilia of 77 per cent.1 This was placed on record together with a review of the literature of this well-known feature of asthma. At about the same time Goldschmidt2 recorded the observation that