│ │ │ │ │ │mitotic figures │ │ │ │ │ │seen. The │ │ │ │ │ │protoplasm is │ │ │ │ │ │homogeneous and │ │ │ │ │ │pale blue or lilac │ │ │ │ │ │in relatively │ │ │ │ │ │large amount. No │ │ │ │ │ │granules were ever │ │ │ │ │ │seen. ────────────────┴────────────┴───────┴───────┴───────┴──────────┴────────────────── It would seem, from a general observation of simple and infected wounds and from a few blood counts, that the response of leucocytes in the lower animals is greater than in monkeys and man. The ease with which animals endure a wound and the rapid local pus formation about an infection speak for an easy mobilization of their cellular defenders; their connective tissue elements seem equally well brought into play. In so far as birds are concerned perhaps the normally large number of leucocytes and the participation of local tissue cells in response to irritation is a preparatory protective mechanism because of their relatively small amount of bone marrow which may not be able to mobilize new cells rapidly; many of the birds, notably those prepared for long flight, have much of their osseous system given over to air space. The number of red blood cells is also greater in Mammalia, which show a variation from 4,000,000 per cubic millimetre in some small genera to 12,000,000 per cubic millimetre in some ungulates, while birds vary from 2–5,000,000 per cubic millimetre. Despite these fundamental differences in the classes, pathological changes of anemia, leucocytosis and leucemia are comparable; polycythemia in lower animals is unknown to me but may of course occur. ANEMIA.