It is suggested that the infarcts occurring in the spleen in malaria may result from an obstruction produced by hyperplasia of the reticular-like cells located within the walls of the venous sinuses. Leucocytes and red blood cells may adhere to the surface of these masses of reticular-like cells since the circulation in malaria is slowed. The normal histological structures in the spleen of different animals are discussed that may predispose to vascular obstruction.