IN human malaria it has long been recognized that total loss of blood is significantly more extensive than loss which can be attributed to the direct rupture of parasites emerging from infected erythrocytes1. In a comparative survey of loss of blood and replacement in plasmodial infections of other mammals and birds, excessive erythrocyte destruction of the same type has been observed in all except one of the host–parasite combinations studied to date, namely in rats with Plasmodium berghei 2, and Plasmodium vinckei 3, in rhesus monkeys with Plasmodium cynomolgi, Plasmodium gonderi, and Plasmodium knowlesi 4, and in chickens with Plasmodium lophurae (Zuckerman, A., unpublished results).