Exactly analogous conditions, occurring spontaneously, have been demonstrated by Leredde and Perrin in the so-called Duehring's disease. The bullae which appear in this dermatosis contain, so long as their contents are clear, chiefly polynuclear eosinophil cells. In a later stage, as is usually the case, bacteria effect an entrance into the bullae, which now become filled with neutrophils. According to modern views on suppuration, the experiment of Neusser and the observation of Leredde and Perrin can only be explained by the hypothesis, that the eosinophil and neutrophil cells, as we have already several times mentioned, are of different chemiotactic irritability. Hence the eosinophil cells only emigrate to those parts where a specific stimulating substance is present. From this point of view experiments and clinical observations known up to the present on eosinophilia may be readily explained. Neusser's experiment for instance may be explained in the following way. In the pemphigus bullae a substance is present that chemiotactically attracts the eosinophils. Hence the cells normally contained in the blood emigrate into them, and produce the picture of an eosinophilous suppuration. Should the disease assume from the first a localised distribution only, the essential feature of the process is excluded. =A totally different appearance, however, is produced= when the disease has attacked large areas. =Under these circumstances large amounts of the specific active agent reach the blood-stream by absorption and diffusion. Here it exercises a strong chemiotactic influence on the physiological storage depot of the eosinophils, the bone-marrow; leading to an increase of the eosinophils of the blood to a greater or less degree. The bone-marrow, according to general biological laws, is by the increased emigration now further stimulated to a fresh production, and during a protracted illness can hence keep up the eosinophilia.=