STUDIES IN COMPARATIVE HÆMATOLOGY.—III. MARSUPIALIA

¹ Department of Biology, New York University, and the New York Zoological Society

Except for a few minor differences the morphology of the leucocytes of the marsupials is similar to that of the leucocytes in man. The white-cell counts vary slightlymabout 8000 is an average figure. The differential counts, in general, resemble those found in man. The polynuclear counts, for most of the marsupials, are more right-handed than the human polynuclear count. The mean diameter of the red cells in the genus Macropus is 8·6 µ; in the wombat the cells are considerably smaller (7·2 µ), and in the opossum considerably larger (9·2 µ). The remarkable feature in connexion with the erythrocytes is the high hæmoglobin content which occurs in the genus Macropus. The red cell counts are distinctly higher than in man (about 8,000,000). The resistance of the red cells to saponin varies considerably, as does the resistance to sodium taurocholate; it is not possible to make any generalisation from the figures obtained. The resistance to hypotonic saline is either the same or a little less than that of the cells of man.