On a Plasmodium (Plasmodium relictum var. spheniscidæ, n. var.), observed in four species of Penguins

Abstract

Summary.An illustrated account is given of Plasmodium relictum n. var. spheniscidæ from the King Penguin, Aptenodytes patagonica, from South Georgia, the Black‐footed Penguin, Spheniscus demersus, from Saldanha Bay, South Africa, the Yellow‐crowned Penguin, Eudyptes antipodes, from Foveaux Strait, New Zealand and the Rock‐hopper Penguin, Eudyptes crestatus, from Gough Island.The variations in the morphology and in the range of dimensions of the Plasmodium from each of the hosts are described and illustrated. Detailed comparison shows that the same organism is present hi all of them.The effects of Plasmodium relictum var. spheniscidæ on the hosts are described in some detail, counts of infected erythrocytes and of parasites are given and the effect of alterations induced in organs of one Black‐footed Penguin are discussed. The parasite level in the different hosts is noted.The identity of the Plasmodium from the four species of Penguin is discussed in some detail, especially in view of the wide distribution of Plasmodium relictum Grassi and Feletti both geographically and in the number and variety of its hosts. Various morphological and physiological strains of P. relictum are noted and induced morphological differences by passages to unusual hosts are considered. The conclusion is reached that a strain or morphological variety of P. relictum is present in Penguins, for which the name Plasmodium relictum n. var. spheniscidæ is proposed.The low gametocyte level of P. relictum var. spheniscidæ in all the hosts seems to indicate that it may be approaching natural agametogony, and so may be on the way to self‐extermination.Tolerance and age‐immunity of hosts and possible susceptibility and immunity among Culicine mosquitoes in relation to avian malaria are briefly noted.The economic importance of avian Plasmodium in general, and possibly of Plasmodium relictum var. spheniscidæ is briefly indicated.