The increase in phagocytic function of neutrophiles of mice was measured during the progressive development of anemia due to blood loss. The animals were bled from the tail, 2 per cent of total body weight being removed twice weekly for nine bleedings. Phagocytosis was 161 per cent of normal at the end of this period, and the erythrocyte totals and hemoglobin values were approximately two thirds of normal. The anemic mice were infected intraperitoneally with a suspension of Salmonella typhimurium and their survival rate was compared with normal mice similarly infected. Twenty-eight of 63 anemic mice survived and 14 of 63 normal mice survived.
In a second experiment, mice were subjected to bleeding every third day for nine bleedings, and were then infected along with a control group. One half of the anemic animals were bled for three additional bleedings after the infection. Two of 48 control animals survived, 5 of 47 anemic mice, additionally bled, survived, and 19 of 47 anemic mice, not bled after infection, survived. This suggests that the increase in phagocytosis that accompanies anemia may be, at least in part, responsible for the increased resistance to infection.