3. The cells of the bone-marrow, on the contrary, and the polynuclear pseudoeosinophil cells do not show the least variation in the course of the first year. Bearing in mind that under normal conditions these cells are met with exclusively in the bone-marrow, and that inflammation in animals after removal of the spleen is accompanied by an acute pseudoeosinophil leucocytosis, exactly as in normal animals, one must admit that the production and function of this kind of cell are quite independent of the spleen. Hence there can be no doubt about their myelogenic nature. 4. It is especially important that the mononuclear and the leucocytes associated with them, undergo no increase. As these cells under normal circumstances occur both in the spleen and in the bone-marrow, we must assume that normally also the bone-marrow is responsible for the majority of this kind in the blood, and that the deficiency in the splenic contribution can be easily covered by a slightly raised activity of the bone-marrow. Were the share of the spleen important, from general biological considerations, an over-production of the kind of cell in question must occur in the vicarious organs. 5. The increase of the eosinophil cells, which constantly makes its appearance in the second year after the operation, is highly interesting, and leads to a really enormous rise in their absolute and relative numbers. Their percentage number once rose to 34.6%, and their absolute quantity amounted at the end of the second year on the average to 30-50-fold their original number (see table). =Hence it follows from Kurloff's researches that the spleen of the guinea-pig plays quite an unimportant part in the formation of the white blood corpuscles, and that after splenectomy in the first year compensation occurs only in the lymph-glands, followed in the second year by a great increase of the eosinophil cells. It is to be particularly insisted once again that the spleen has nothing at all to do with the formation of the pseudoeosinophil polynuclear cells, which are the analogues of the polynuclear neutrophils of man.= * * * * * How do observations on man stand in the light of Kurloff's observations, which might be regarded as depending on peculiarities of the particular kind of animal?