=These pseudoeosinophil, polynuclear cells, correspond functionally to the neutrophil polynuclear of man=; their number amounts to 40-50% of the total white cells. The red bone-marrow is to be regarded as the place of origin of this kind of cell. It contains very many pseudoeosinophil cells, and indeed all stages are to be found in it, from the mononuclear cells bearing granules to the fully formed polynuclear. 2. The typical =eosinophil leucocytes=, which fully correspond to those found in man, and amount to about 10% of the number of the white. 3. The "=nigrosinophil cells=," as they are called by Kurloff. In their general appearance, in the size of the cell and the granulation, they completely correspond to the eosinophil cell. The only distinction between them consists in a chemical difference in the granulation. These cells stain in the colour of nigrosin in the aurantia-eosin-nigrosin mixture, whilst the eosinophil cells become red. The two granulations always show different shades in the triacid preparation as well; for the nigrosinophil cells stain a blacker hue. II. Cells free from granules. ([alpha]) Cells with vacuoles. This is a quite peculiar group, characteristic for the blood of the guinea-pig. It shews transitions in the blood, from large mononuclear to transitional and polynuclear forms, but is marked by the lack of any kind of granulation. Instead of the latter, we find in these cells a roundish, nucleus-like form in the protoplasm, which also takes the nuclear stains, and possibly is to be considered an accessory nucleus. We have received the impression that we have here to deal with a vacuole filled with substance secreted by the cell. In a large series of preparations, it is possible to obtain some elucidation of the development and fate of these appearances. They first appear as point-like granules in the protoplasm, bearing no relation to the cell nucleus; they gradually increase, and acquire a considerable circumference. When they have attained about the size of the cell nucleus, they, or rather their contents, appear to break through the protoplasmic membrane and to leave the cell. The number of the vacuole containing cells is 15-20% of the colourless blood corpuscles. ([beta]) Typical lymphocytes. Their appearance completely corresponds with that of human lymphocytes as described above. They make up 30-35% of the total number of leucocytes.