A post-operative eosinophilia, the existence of which has already been put foreward in our previous papers, has been discussed especially on the myelogram, and on its relation to the peri-pheral blood picture. The details are as follows 1) Both at the period of post-operative eosinopenia and eosinophilia, eosinophile leucocytes in the bone marrow show a shift to the right to a certain extent, as compared with those in the peripheral blood, its maximum being at the period of eosinophilia. Moreover, the number of eosinophile leucocytes in the bone marrow also increases at the period of peripheral eosinophilia. 2) The migratory ability of the peripheral eosinophile leucocytes descends at the period of the post-operative eosinopenia, while at t...