Abstract
A non-splenectomized dog, on a vitamin-adequate basal diet, in the course of a plasmapheresis experiment, developed an uncontrollable anemia associated with the presence of bodies in or on the erythrocytes, indistinguishable from the descriptions of Bartonella canis. The normal plasma protein level of 7.3 per cent was reduced to 4.1 per cent by diet and the removal of 5354 ml. of whole blood in 33 bleedings. The Bartonella infection was transferred to a splenectomized dog by an intravenous injection of whole blood. Each animal was apparently sterilized by one injection of neoarsphenamine equivalent to 15 mg. per kilo weight. It is possible that the spleen liberates some substance into the blood stream which has an inhibitory effect upon a latent Bartonella infection and that this protective substance was diminished by the many bleedings associated with the lowering of plasma proteins in the non-splenectomized dog and was lacking in the inoculated splenectomized dog.